From 3817896ae7964a55eec32b127ee2c5ba599a377c Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Thu, 23 May 2019 12:26:53 -0700
Subject: [PATCH 01/12] transaction apps

---
 app/baby.hoon |  38 +++++++++++++
 lib/tapp.hoon | 155 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/trad.hoon | 142 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 335 insertions(+)
 create mode 100644 app/baby.hoon
 create mode 100644 lib/tapp.hoon
 create mode 100644 lib/trad.hoon

diff --git a/app/baby.hoon b/app/baby.hoon
new file mode 100644
index 000000000..7a09dc0f4
--- /dev/null
+++ b/app/baby.hoon
@@ -0,0 +1,38 @@
+/+  tapp
+::
+::  Preamble
+::
+=>
+  |%
+  +$  state
+    $:  count=@ud
+    ==
+  +$  command  cord
+  ++  tapp  (^tapp state command)
+  --
+=,  create-tapp=create-tapp:tapp
+=,  trad=trad:tapp
+=,  tapp-core=tapp-core:tapp
+=,  tapp-trad=tapp-trad:tapp
+=,  helpers:tapp
+::
+::  The app
+::
+%-  create-tapp
+^-  tapp-core
+|_  [=bowl:gall state]
+++  handle-command
+  |=  =command
+  =/  m  tapp-trad
+  ^-  form:m
+  =/  =hiss:eyre
+    :*  purl=(rash command auri:de-purl:html)
+        meth=%get
+        math=~
+        body=~
+    ==
+  ;<  ~           bind:m  (send-hiss hiss)
+  ;<  =httr:eyre  bind:m  expect-sigh
+  ~&  [%fetched count httr]
+  (pure:m +(count))
+--
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
new file mode 100644
index 000000000..6cba68dda
--- /dev/null
+++ b/lib/tapp.hoon
@@ -0,0 +1,155 @@
+/+  trad
+=,  trad-lib=trad
+|*  [state-type=mold command-type=mold]
+|%
+::
+::  The form of a tapp
+::
+++  tapp-core
+  $_  ^|
+  |_  [bowl:gall state-type]
+  ++  handle-command
+    |~  command-type
+    *form:tapp-trad
+  --
+::
+++  trad-lib  (^trad-lib sign card)
+++  trad  trad:trad-lib
+::
+::  Possible async calls
+::
++$  card
+  $%  [%hiss wire ~ %httr %hiss hiss:eyre]
+  ==
+::
+::  Possible async responses
+::
++$  sign
+  $%  [%sigh =httr:eyre]
+  ==
++$  move  (pair bone card)
+++  tapp-trad  (trad state-type)
++$  tapp-state
+  $:  waiting=(qeu command-type)
+      active=(unit eval-form:eval:tapp-trad)
+      app-state=state-type
+  ==
+++  helpers
+  =,  trad-input=trad-input:trad-lib
+  |%
+  ++  just-do
+    |=  =card
+    =/  m  (trad ,~)
+    ^-  form:m
+    |=  trad-input
+    [[/ card]~ ~ %done ~]
+  ::
+  ++  send-hiss
+    |=  =hiss:eyre
+    =/  m  (trad ,~)
+    ^-  form:m
+    (just-do %hiss / ~ %httr %hiss hiss)
+  ::
+  ++  expect-sigh
+    =/  m  (trad ,httr:eyre)
+    ^-  form:m
+    |=  =trad-input
+    ?~  trad-input
+      [~ ~ %wait ~]
+    ?:  ?=(%sigh -.u.trad-input)
+      [~ ~ %done httr.u.trad-input]
+    ~|  [%expected-sigh got=-.u.trad-input]
+    !!
+  --
+++  create-tapp
+  |=  handler=tapp-core
+  |_  [=bowl:gall tapp-state]
+  ++  this-tapp  .
+  ::
+  ::  Start a command
+  ::
+  ++  poke-noun
+    |=  command=command-type
+    ^-  (quip move _this-tapp)
+    =.  waiting  (~(put to waiting) command)
+    ?^  active
+      ~&  [%waiting-until-current-trad-finishes waiting]
+      `this-tapp
+    start-trad
+  ::
+  ::  Pass response to trad
+  ::
+  ++  sigh-httr
+    |=  [=wire =httr:eyre]
+    ^-  (quip move _this-tapp)
+    (take-trad `[%sigh httr])
+  ::
+  ::  Failed http request
+  ::
+  ++  sigh-tang
+    |=  [=wire =tang]
+    ^-  (quip move _this-tapp)
+    (fail-trad %failed-sigh tang)
+  ::
+  ::  Continue computing trad
+  ::
+  ++  take-trad
+    |=  =trad-input:trad-lib
+    ^-  (quip move _this-tapp)
+    =/  m  tapp-trad
+    ?~  active
+      ~|  %no-active-trad  !!
+    =^  r=[moves=(list move) =eval-result:eval:m]  u.active
+      (take:eval:m u.active ost.bowl /trad trad-input)
+    =>  .(active `(unit eval-form:eval:tapp-trad)`active)  :: TMI
+    =^  moves=(list move)  this-tapp
+      ?-  -.eval-result.r
+        %next  `this-tapp
+        %fail  (fail-trad err.eval-result.r)
+        %done  (done-trad value.eval-result.r)
+      ==
+    [(weld moves.r moves) this-tapp]
+  ::
+  ::  Called on trad failure
+  ::
+  ++  fail-trad
+    |=  err=(pair term tang)
+    ^-  (quip move _this-tapp)
+    %-  (slog leaf+"tapp command failed" leaf+(trip p.err) q.err)
+    finish-trad
+  ::
+  ::  Called on trad success
+  ::
+  ++  done-trad
+    |=  state=state-type
+    ^-  (quip move _this-tapp)
+    ~&  %trad-done
+    =.  app-state  state
+    finish-trad
+  ::
+  ::  Called whether trad failed or succeeded
+  ::
+  ++  finish-trad
+    ^-  (quip move _this-tapp)
+    =.  active   ~
+    =.  waiting  +:~(get to waiting)
+    start-trad
+  ::
+  ::  Try to start next command
+  ::
+  ++  start-trad
+    ^-  (quip move _this-tapp)
+    ?.  =(~ active)
+      ~|  %trad-already-active  !!
+    =/  next=(unit command-type)  ~(top to waiting)
+    ?~  next
+      `this-tapp
+    =.  active
+      :-  ~
+      ^-  eval-form:eval:tapp-trad
+      %-  from-form:eval:tapp-trad
+      ^-  form:tapp-trad
+      (~(handle-command handler bowl app-state) u.next)
+    (take-trad ~)
+  --
+--
diff --git a/lib/trad.hoon b/lib/trad.hoon
new file mode 100644
index 000000000..2dedde904
--- /dev/null
+++ b/lib/trad.hoon
@@ -0,0 +1,142 @@
+|*  [input-type=mold card-type=mold]
+|%
++$  trad-input  (unit input-type)
++$  trad-move  (pair bone card-type)
+::
+::  notes:   notes to send immediately.  These will go out even if a
+::           later stage of the process fails, so they shouldn't have any
+::           semantic effect on the rest of the system.  Path is
+::           included exclusively for documentation and |verb.
+::  effects: moves to send after the process ends.
+::  wait:    don't move on, stay here.  The next sign should come back
+::           to this same callback.
+::  cont:    continue process with new callback.
+::  fail:    abort process; don't send effects
+::  done:    finish process; send effects
+::
+++  trad-output-raw
+  |*  a=mold
+  $~  [~ ~ %done *a]
+  $:  notes=(list [path card-type])
+      effects=(list card-type)
+      $=  next
+      $%  [%wait ~]
+          [%cont self=(trad-form-raw a)]
+          [%fail err=(pair term tang)]
+          [%done value=a]
+      ==
+  ==
+::
+++  trad-form-raw
+  |*  a=mold
+  $-(trad-input (trad-output-raw a))
+::
+++  trad-fail
+  |=  err=(pair term tang)
+  |=  trad-input
+  [~ ~ %fail err]
+::
+++  trad
+  |*  a=mold
+  |%
+  ++  output  (trad-output-raw a)
+  ++  form  (trad-form-raw a)
+  ++  pure
+    |=  arg=a
+    ^-  form
+    |=  trad-input
+    [~ ~ %done arg]
+  ::
+  ++  bind
+    |*  b=mold
+    |=  [m-b=(trad-form-raw b) fun=$-(b form)]
+    ^-  form
+    |=  input=trad-input
+    =/  b-res=(trad-output-raw b)
+      (m-b input)
+    ^-  output
+    :+  notes.b-res  effects.b-res
+    ?-    -.next.b-res
+      %wait  [%wait ~]
+      %cont  [%cont ..$(m-b self.next.b-res)]
+      %fail  [%fail err.next.b-res]
+      %done  [%cont (fun value.next.b-res)]
+    ==
+  ::
+  ::  The trad monad must be evaluted in a particular way to maintain
+  ::  its monadic character.  +take:eval implements this.
+  ::
+  ++  eval
+    |%
+    ::  Indelible state of a trad
+    ::
+    +$  eval-form
+      $:  effects=(list card-type)
+          =form
+      ==
+    ::
+    ::  Convert initial form to eval-form
+    ::
+    ++  from-form
+      |=  =form
+      ^-  eval-form
+      [~ form]
+    ::
+    ::  The cases of results of +take
+    ::
+    +$  eval-result
+      $%  [%next ~]
+          [%fail err=(pair term tang)]
+          [%done value=a]
+      ==
+    ::
+    ::  Take a new sign and run the trad against it
+    ::
+    ++  take
+      ::  moves: accumulate throughout recursion the moves to be
+      ::         produced now
+      =|  moves=(list trad-move)
+      |=  [=eval-form =bone =our=wire =trad-input]
+      ^-  [[(list trad-move) =eval-result] _eval-form]
+      ::  run the trad callback
+      ::
+      =/  =output  (form.eval-form trad-input)
+      ::  add notes to moves
+      ::
+      =.  moves
+        %+  welp
+          moves
+        %+  turn  notes.output
+        |=  [=path card=card-type]
+        ^-  trad-move
+        [bone card]
+      ::  add effects to list to be produced when done
+      ::
+      =.  effects.eval-form
+        (weld effects.eval-form effects.output)
+      ::  if done, produce effects
+      ::
+      =?  moves  ?=(%done -.next.output)
+        %+  welp
+          moves
+        %+  turn  effects.eval-form
+        |=  card=card-type
+        ^-  trad-move
+        [bone card]
+      ::  case-wise handle next steps
+      ::
+      ?-  -.next.output
+          %wait  [[moves %next ~] eval-form]
+          %fail  [[moves %fail err.next.output] eval-form]
+          %done  [[moves %done value.next.output] eval-form]
+          %cont
+        ::  recurse to run continuation with initialization input
+        ::
+        %_  $
+          form.eval-form  self.next.output
+          trad-input      ~
+        ==
+      ==
+    --
+  --
+--

From ece6bba79b91fb40d9a9f691056665a78f254ee1 Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Fri, 24 May 2019 19:42:37 -0700
Subject: [PATCH 02/12] bigger poc

---
 app/baby.hoon | 103 ++++++++++++++++++++++++++++++++++++++++++--------
 lib/tapp.hoon |  42 +++++++++++++++++++-
 2 files changed, 129 insertions(+), 16 deletions(-)

diff --git a/app/baby.hoon b/app/baby.hoon
index 7a09dc0f4..5fd5dd223 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -1,3 +1,8 @@
+::  Little app to demonstrate the structure of programs written with the
+::  transaction monad.
+::
+::  Fetches the top comment of each of the top 10 stories from Hacker News
+::
 /+  tapp
 ::
 ::  Preamble
@@ -5,34 +10,102 @@
 =>
   |%
   +$  state
-    $:  count=@ud
+    $:  top-comments=(list tape)
     ==
   +$  command  cord
   ++  tapp  (^tapp state command)
+  ::
   --
-=,  create-tapp=create-tapp:tapp
+=>
+  |%
+  ::  Helper function to print a comment
+  ::
+  ++  comment-to-tang
+    |=  =tape
+    ^-  tang
+    %+  welp
+      %+  turn  (rip 10 (crip tape))
+      |=  line=cord
+      leaf+(trip line)
+    [leaf+""]~
+  ::
+  ::  All the URLs we fetch from
+  ::
+  ++  urls
+    =/  base  "https://hacker-news.firebaseio.com/v0/"
+    :*  top-stories=(weld base "topstories.json")
+        item=|=(item=@ud `tape`:(welp base "item/" +>:(scow %ui item) ".json"))
+    ==
+--
 =,  trad=trad:tapp
-=,  tapp-core=tapp-core:tapp
 =,  tapp-trad=tapp-trad:tapp
 =,  helpers:tapp
 ::
 ::  The app
 ::
-%-  create-tapp
-^-  tapp-core
+%-  create-tapp:tapp
+^-  tapp-core:tapp
 |_  [=bowl:gall state]
+::
+::  Main function
+::
 ++  handle-command
   |=  =command
   =/  m  tapp-trad
   ^-  form:m
-  =/  =hiss:eyre
-    :*  purl=(rash command auri:de-purl:html)
-        meth=%get
-        math=~
-        body=~
-    ==
-  ;<  ~           bind:m  (send-hiss hiss)
-  ;<  =httr:eyre  bind:m  expect-sigh
-  ~&  [%fetched count httr]
-  (pure:m +(count))
+  ::
+  ::  If requested to print, just print what we have in our state
+  ::
+  ?:  =(command 'print')
+    ~&  'Top comments:'
+    %-  (slog (zing (turn top-comments comment-to-tang)))
+    (pure:m top-comments)
+  ::
+  ::  Otherwise, fetch the top HN stories
+  ::
+  =.  top-comments  ~
+  ;<  =top-stories=json  bind:m  (fetch-json top-stories:urls)
+  =/  top-stories=(list @ud)
+    ((ar ni):dejs:format top-stories-json)
+  ::
+  ::  Loop through the first 10 stories
+  ::
+  =.  top-stories  (scag 10 top-stories)
+  |-  ^-  form:m
+  =*  loop  $
+  ::
+  ::  If done, print the results
+  ::
+  ?~  top-stories
+    (handle-command 'print')
+  ::
+  ::  Else, fetch the story info
+  ::
+  ~&  "fetching item #{+>:(scow %ui i.top-stories)}"
+  ;<  =story-info=json  bind:m  (fetch-json (item:urls i.top-stories))
+  =/  story-comments=(unit (list @ud))
+    ((ot kids+(ar ni) ~):dejs-soft:format story-info-json)
+  ::
+  ::  If no comments, say so
+  ::
+  ?:  |(?=(~ story-comments) ?=(~ u.story-comments))
+    =.  top-comments  ["<no top comment>" top-comments]
+    loop(top-stories t.top-stories)
+  ::
+  ::  Else, fetch comment info
+  ::
+  ;<  =comment-info=json  bind:m  (fetch-json (item:urls i.u.story-comments))
+  =/  comment-text=(unit tape)
+    ((ot text+sa ~):dejs-soft:format comment-info-json)
+  ::
+  ::  If no text (eg comment deleted), record that
+  ::
+  ?~  comment-text
+    =.  top-comments  ["<top comment has no text>" top-comments]
+    loop(top-stories t.top-stories)
+  ::
+  ::  Else, add text to state
+  ::
+  =.  top-comments  [u.comment-text top-comments]
+  loop(top-stories t.top-stories)
 --
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index 6cba68dda..855e1246d 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -60,11 +60,52 @@
       [~ ~ %done httr.u.trad-input]
     ~|  [%expected-sigh got=-.u.trad-input]
     !!
+  ::
+  ++  extract-httr-body
+    |=  =httr:eyre
+    =/  m  (trad ,cord)
+    ^-  form:m
+    ?.  =(2 (div p.httr 100))
+      (trad-fail:trad-lib %httr-error >p.httr< >+.httr< ~)
+    ?~  r.httr
+      (trad-fail:trad-lib %expected-httr-body >httr< ~)
+    (pure:m q.u.r.httr)
+  ::
+  ++  parse-json
+    |=  =cord
+    =/  m  (trad ,json)
+    ^-  form:m
+    =/  json=(unit json)  (de-json:html cord)
+    ?~  json
+      (trad-fail:trad-lib %json-parse-error ~)
+    (pure:m u.json)
+  ::
+  ++  fetch-json
+    |=  url=tape
+    =/  m  (trad ,json)
+    ^-  form:m
+    =/  =hiss:eyre
+      :*  purl=(scan url auri:de-purl:html)
+          meth=%get
+          math=~
+          body=~
+      ==
+    ;<  ~           bind:m  (send-hiss hiss)
+    ;<  =httr:eyre  bind:m  expect-sigh
+    ;<  =cord       bind:m  (extract-httr-body httr)
+    (parse-json cord)
   --
 ++  create-tapp
   |=  handler=tapp-core
   |_  [=bowl:gall tapp-state]
   ++  this-tapp  .
+  ++  prep
+    |=  old-state=*
+    ^-  (quip move _this-tapp)
+    =/  old  ((soft tapp-state) old-state)
+    ?~  old
+      `this-tapp
+    `this-tapp(+<+ u.old)
   ::
   ::  Start a command
   ::
@@ -123,7 +164,6 @@
   ++  done-trad
     |=  state=state-type
     ^-  (quip move _this-tapp)
-    ~&  %trad-done
     =.  app-state  state
     finish-trad
   ::

From 9eb10aaec177f9c984018534df9745e2a63c6c33 Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Sat, 25 May 2019 19:17:18 -0700
Subject: [PATCH 03/12] better stdio

---
 app/baby.hoon | 11 +++++--
 lib/tapp.hoon | 83 +++++++--------------------------------------------
 2 files changed, 19 insertions(+), 75 deletions(-)

diff --git a/app/baby.hoon b/app/baby.hoon
index 5fd5dd223..48caf4b70 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -3,7 +3,7 @@
 ::
 ::  Fetches the top comment of each of the top 10 stories from Hacker News
 ::
-/+  tapp
+/+  tapp, stdio
 ::
 ::  Preamble
 ::
@@ -14,7 +14,6 @@
     ==
   +$  command  cord
   ++  tapp  (^tapp state command)
-  ::
   --
 =>
   |%
@@ -39,7 +38,7 @@
 --
 =,  trad=trad:tapp
 =,  tapp-trad=tapp-trad:tapp
-=,  helpers:tapp
+=,  stdio
 ::
 ::  The app
 ::
@@ -57,6 +56,8 @@
   ::  If requested to print, just print what we have in our state
   ::
   ?:  =(command 'print')
+    ~&  'drumroll please...'
+    ;<  ~  bind:m  (wait (add now.bowl ~s5))
     ~&  'Top comments:'
     %-  (slog (zing (turn top-comments comment-to-tang)))
     (pure:m top-comments)
@@ -64,6 +65,10 @@
   ::  Otherwise, fetch the top HN stories
   ::
   =.  top-comments  ~
+  ::
+  ::  If this whole thing takes more than 5 seconds, cancel it
+  ::
+  %+  (set-timeout _top-comments)  (add now.bowl ~s5)
   ;<  =top-stories=json  bind:m  (fetch-json top-stories:urls)
   =/  top-stories=(list @ud)
     ((ar ni):dejs:format top-stories-json)
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index 855e1246d..3e359075f 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -1,4 +1,7 @@
+/-  tapp
 /+  trad
+=,  card=card:tapp
+=,  sign=sign:tapp
 =,  trad-lib=trad
 |*  [state-type=mold command-type=mold]
 |%
@@ -16,17 +19,6 @@
 ++  trad-lib  (^trad-lib sign card)
 ++  trad  trad:trad-lib
 ::
-::  Possible async calls
-::
-+$  card
-  $%  [%hiss wire ~ %httr %hiss hiss:eyre]
-  ==
-::
-::  Possible async responses
-::
-+$  sign
-  $%  [%sigh =httr:eyre]
-  ==
 +$  move  (pair bone card)
 ++  tapp-trad  (trad state-type)
 +$  tapp-state
@@ -34,67 +26,6 @@
       active=(unit eval-form:eval:tapp-trad)
       app-state=state-type
   ==
-++  helpers
-  =,  trad-input=trad-input:trad-lib
-  |%
-  ++  just-do
-    |=  =card
-    =/  m  (trad ,~)
-    ^-  form:m
-    |=  trad-input
-    [[/ card]~ ~ %done ~]
-  ::
-  ++  send-hiss
-    |=  =hiss:eyre
-    =/  m  (trad ,~)
-    ^-  form:m
-    (just-do %hiss / ~ %httr %hiss hiss)
-  ::
-  ++  expect-sigh
-    =/  m  (trad ,httr:eyre)
-    ^-  form:m
-    |=  =trad-input
-    ?~  trad-input
-      [~ ~ %wait ~]
-    ?:  ?=(%sigh -.u.trad-input)
-      [~ ~ %done httr.u.trad-input]
-    ~|  [%expected-sigh got=-.u.trad-input]
-    !!
-  ::
-  ++  extract-httr-body
-    |=  =httr:eyre
-    =/  m  (trad ,cord)
-    ^-  form:m
-    ?.  =(2 (div p.httr 100))
-      (trad-fail:trad-lib %httr-error >p.httr< >+.httr< ~)
-    ?~  r.httr
-      (trad-fail:trad-lib %expected-httr-body >httr< ~)
-    (pure:m q.u.r.httr)
-  ::
-  ++  parse-json
-    |=  =cord
-    =/  m  (trad ,json)
-    ^-  form:m
-    =/  json=(unit json)  (de-json:html cord)
-    ?~  json
-      (trad-fail:trad-lib %json-parse-error ~)
-    (pure:m u.json)
-  ::
-  ++  fetch-json
-    |=  url=tape
-    =/  m  (trad ,json)
-    ^-  form:m
-    =/  =hiss:eyre
-      :*  purl=(scan url auri:de-purl:html)
-          meth=%get
-          math=~
-          body=~
-      ==
-    ;<  ~           bind:m  (send-hiss hiss)
-    ;<  =httr:eyre  bind:m  expect-sigh
-    ;<  =cord       bind:m  (extract-httr-body httr)
-    (parse-json cord)
-  --
 ++  create-tapp
   |=  handler=tapp-core
   |_  [=bowl:gall tapp-state]
@@ -102,6 +33,7 @@
   ++  prep
     |=  old-state=*
     ^-  (quip move _this-tapp)
+    ~&  %tapp-loaded
     =/  old  ((soft tapp-state) old-state)
     ?~  old
       `this-tapp
@@ -132,6 +64,13 @@
     ^-  (quip move _this-tapp)
     (fail-trad %failed-sigh tang)
   ::
+  ++  wake
+    |=  [=wire error=(unit tang)]
+    ^-  (quip move _this-tapp)
+    ?^  error
+      (fail-trad %timer-fire-failed u.error)
+    (take-trad `[%wake ~])
+  ::
   ::  Continue computing trad
   ::
   ++  take-trad

From 2fd87c815b538d8d433686709a23bef2cebb58aa Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Sat, 25 May 2019 22:14:08 -0700
Subject: [PATCH 04/12] add contracts to trad and time-related stdio functions

---
 app/baby.hoon  |  11 +--
 lib/stdio.hoon | 184 +++++++++++++++++++++++++++++++++++++++++++++++++
 lib/tapp.hoon  |  60 ++++++++++++----
 lib/trad.hoon  |  58 ++++++++++++----
 sur/tapp.hoon  |  25 +++++++
 5 files changed, 305 insertions(+), 33 deletions(-)
 create mode 100644 lib/stdio.hoon
 create mode 100644 sur/tapp.hoon

diff --git a/app/baby.hoon b/app/baby.hoon
index 48caf4b70..850d50e26 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -57,7 +57,8 @@
   ::
   ?:  =(command 'print')
     ~&  'drumroll please...'
-    ;<  ~  bind:m  (wait (add now.bowl ~s5))
+    ;<  now=@da  bind:m  get-time
+    ;<  ~        bind:m  (wait (add now ~s3))
     ~&  'Top comments:'
     %-  (slog (zing (turn top-comments comment-to-tang)))
     (pure:m top-comments)
@@ -66,16 +67,16 @@
   ::
   =.  top-comments  ~
   ::
-  ::  If this whole thing takes more than 5 seconds, cancel it
+  ::  If this whole thing takes more than 15 seconds, cancel it
   ::
-  %+  (set-timeout _top-comments)  (add now.bowl ~s5)
+  %+  (set-timeout _top-comments)  (add now.bowl ~s15)
   ;<  =top-stories=json  bind:m  (fetch-json top-stories:urls)
   =/  top-stories=(list @ud)
     ((ar ni):dejs:format top-stories-json)
   ::
-  ::  Loop through the first 10 stories
+  ::  Loop through the first 5 stories
   ::
-  =.  top-stories  (scag 10 top-stories)
+  =.  top-stories  (scag 5 top-stories)
   |-  ^-  form:m
   =*  loop  $
   ::
diff --git a/lib/stdio.hoon b/lib/stdio.hoon
new file mode 100644
index 000000000..44fafa4da
--- /dev/null
+++ b/lib/stdio.hoon
@@ -0,0 +1,184 @@
+::  Standard input/input functions.
+::
+::  These are all asynchronous computations, which means they produce a
+::  form:(trad A) for some type A.  You can always tell what they
+::  produce by checking their first three lines.
+::
+::  Functions with the word "raw" in their name are for internal use
+::  only because they carry a high salmonella risk.  More specifcally,
+::  improper use of them may result in side effects that the tapp
+::  runtime doesn't know about and can't undo in case the transaction
+::  fails.
+::
+/-  tapp-sur=tapp
+/+  trad
+=,  card=card:tapp-sur
+=,  sign=sign:tapp-sur
+=,  contract=contract:tapp-sur
+=+  (trad sign card contract)
+|%
+::
+::  Raw power
+::
+++  send-raw-card
+  |=  =card
+  =/  m  (trad ,~)
+  ^-  form:m
+  |=  trad-input
+  [[/ card]~ ~ ~ %done ~]
+::
+::  Add or remove a contract
+::
+++  set-raw-contract
+  |=  [add=? =contract]
+  =/  m  (trad ,~)
+  ^-  form:m
+  |=  trad-input
+  [~ ~ (silt [add contract]~) %done ~]
+::
+::    ----
+::
+::  HTTP requests
+::
+++  send-hiss
+  |=  =hiss:eyre
+  =/  m  (trad ,~)
+  ^-  form:m
+  ;<  ~  bind:m  (send-raw-card %hiss / ~ %httr %hiss hiss)
+  (set-raw-contract & %hiss ~)
+::
+::  Wait until we get an HTTP response
+::
+++  take-sigh-raw
+  =/  m  (trad ,httr:eyre)
+  ^-  form:m
+  |=  =trad-input
+  :^  ~  ~  ~
+  ?~  in.trad-input
+    [%wait ~]
+  ?.  ?=(%sigh -.sign.u.in.trad-input)
+    [%fail %expected-sigh >got=-.sign.u.in.trad-input< ~]
+  [%done httr.sign.u.in.trad-input]
+::
+::  Wait until we get an HTTP response and unset contract
+::
+++  take-sigh
+  =/  m  (trad ,httr:eyre)
+  ^-  form:m
+  ;<  =httr:eyre  bind:m  take-sigh-raw
+  ;<  ~           bind:m  (set-raw-contract | %hiss ~)
+  (pure:m httr)
+::
+::  Extract body from raw httr
+::
+++  extract-httr-body
+  |=  =httr:eyre
+  =/  m  (trad ,cord)
+  ^-  form:m
+  ?.  =(2 (div p.httr 100))
+    (trad-fail %httr-error >p.httr< >+.httr< ~)
+  ?~  r.httr
+    (trad-fail %expected-httr-body >httr< ~)
+  (pure:m q.u.r.httr)
+::
+::  Parse cord to json
+::
+++  parse-json
+  |=  =cord
+  =/  m  (trad ,json)
+  ^-  form:m
+  =/  json=(unit json)  (de-json:html cord)
+  ?~  json
+    (trad-fail %json-parse-error ~)
+  (pure:m u.json)
+::
+::  Fetch json at given url
+::
+++  fetch-json
+  |=  url=tape
+  =/  m  (trad ,json)
+  ^-  form:m
+  =/  =hiss:eyre
+    :*  purl=(scan url auri:de-purl:html)
+        meth=%get
+        math=~
+        body=~
+    ==
+  ;<  ~           bind:m  (send-hiss hiss)
+  ;<  =httr:eyre  bind:m  take-sigh
+  ;<  =cord       bind:m  (extract-httr-body httr)
+  (parse-json cord)
+::
+::    ----
+::
+::  Time is what keeps everything from happening at once
+::
+++  get-time
+  =/  m  (trad ,@da)
+  ^-  form:m
+  |=  =trad-input
+  [~ ~ ~ %done now.bowl.trad-input]
+::
+::  Set a timer
+::
+++  send-wait
+  |=  at=@da
+  =/  m  (trad ,~)
+  ^-  form:m
+  ;<  ~  bind:m  (send-raw-card %wait /(scot %da at) at)
+  (set-raw-contract & %wait at)
+::
+::  Wait until we get a wake event
+::
+++  take-wake-raw
+  =/  m  (trad ,@da)
+  ^-  form:m
+  |=  =trad-input
+  :^  ~  ~  ~
+  ?~  in.trad-input
+    [%wait ~]
+  ?.  ?=(%wake -.sign.u.in.trad-input)
+    [%fail %expected-wake >got=-.sign.u.in.trad-input< ~]
+  ?~  wire.u.in.trad-input
+    [%fail %expected-wake-time ~]
+  =/  at=(unit @da)  (slaw %da i.wire.u.in.trad-input)
+  ?~  at
+    [%fail %expected-wake-time-da >wire< ~]
+  [%done u.at]
+::
+::  Wait until we get a wake event and unset contract
+::
+++  take-wake
+  =/  m  (trad ,~)
+  ^-  form:m
+  ;<  at=@da  bind:m  take-wake-raw
+  (set-raw-contract | %wait at)
+::
+::  Wait until time
+::
+++  wait
+  |=  until=@da
+  =/  m  (trad ,~)
+  ^-  form:m
+  ;<  ~  bind:m  (send-wait until)
+  take-wake
+::
+::  Cancel computation if not done by time
+::
+++  set-timeout
+  |*  computation-result=mold
+  =/  m  (trad ,computation-result)
+  |=  [when=@da computation=form:m]
+  ^-  form:m
+  ;<  ~  bind:m  (send-wait when)
+  |=  =trad-input
+  =*  loop  $
+  ?:  ?&  ?=([~ * %wake *] in.trad-input)
+          =(/(scot %da when) wire.u.in.trad-input)
+      ==
+    [~ ~ (silt [| %wait when]~) %fail %trad-timeout ~]
+  =/  c-res  (computation trad-input)
+  ?.  ?=(%cont -.next.c-res)
+    c-res
+  c-res(self.next ..loop(computation self.next.c-res))
+--
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index 3e359075f..3d24b281b 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -2,6 +2,7 @@
 /+  trad
 =,  card=card:tapp
 =,  sign=sign:tapp
+=,  contract=contract:tapp
 =,  trad-lib=trad
 |*  [state-type=mold command-type=mold]
 |%
@@ -16,7 +17,7 @@
     *form:tapp-trad
   --
 ::
-++  trad-lib  (^trad-lib sign card)
+++  trad-lib  (^trad-lib sign card contract)
 ++  trad  trad:trad-lib
 ::
 +$  move  (pair bone card)
@@ -55,21 +56,21 @@
   ++  sigh-httr
     |=  [=wire =httr:eyre]
     ^-  (quip move _this-tapp)
-    (take-trad `[%sigh httr])
+    (take-trad bowl `[wire %sigh httr])
   ::
   ::  Failed http request
   ::
   ++  sigh-tang
     |=  [=wire =tang]
     ^-  (quip move _this-tapp)
-    (fail-trad %failed-sigh tang)
+    (oob-fail-trad %failed-sigh tang)
   ::
   ++  wake
     |=  [=wire error=(unit tang)]
     ^-  (quip move _this-tapp)
     ?^  error
-      (fail-trad %timer-fire-failed u.error)
-    (take-trad `[%wake ~])
+      (oob-fail-trad %timer-fire-failed u.error)
+    (take-trad bowl `[wire %wake ~])
   ::
   ::  Continue computing trad
   ::
@@ -78,41 +79,55 @@
     ^-  (quip move _this-tapp)
     =/  m  tapp-trad
     ?~  active
+      ::  Can't cancel HTTP requests, so we might get answers after end
+      ::  of computation
+      ::
+      ?:  ?=([~ @ %sigh *] in.trad-input)
+        `this-tapp
       ~|  %no-active-trad  !!
     =^  r=[moves=(list move) =eval-result:eval:m]  u.active
-      (take:eval:m u.active ost.bowl /trad trad-input)
+      (take:eval:m u.active ost.bowl trad-input)
     =>  .(active `(unit eval-form:eval:tapp-trad)`active)  :: TMI
     =^  moves=(list move)  this-tapp
       ?-  -.eval-result.r
         %next  `this-tapp
-        %fail  (fail-trad err.eval-result.r)
-        %done  (done-trad value.eval-result.r)
+        %fail  (fail-trad [contracts err]:eval-result.r)
+        %done  (done-trad [contracts value]:eval-result.r)
       ==
     [(weld moves.r moves) this-tapp]
   ::
+  ::  Fails currently-running trad
+  ::
+  ++  oob-fail-trad
+    (cury fail-trad contracts:(need active))
+  ::
   ::  Called on trad failure
   ::
   ++  fail-trad
-    |=  err=(pair term tang)
+    |=  [contracts=(set contract) err=(pair term tang)]
     ^-  (quip move _this-tapp)
     %-  (slog leaf+"tapp command failed" leaf+(trip p.err) q.err)
-    finish-trad
+    (finish-trad contracts)
   ::
   ::  Called on trad success
   ::
   ++  done-trad
-    |=  state=state-type
+    |=  [contracts=(set contract) state=state-type]
     ^-  (quip move _this-tapp)
     =.  app-state  state
-    finish-trad
+    (finish-trad contracts)
   ::
   ::  Called whether trad failed or succeeded
   ::
   ++  finish-trad
+    |=  contracts=(set contract)
     ^-  (quip move _this-tapp)
+    =^  moves-1  this-tapp  (cancel-contracts contracts)
     =.  active   ~
     =.  waiting  +:~(get to waiting)
-    start-trad
+    =^  moves-2  this-tapp  start-trad
+    [(weld moves-1 moves-2) this-tapp]
+  ::
   ::
   ::  Try to start next command
   ::
@@ -129,6 +144,23 @@
       %-  from-form:eval:tapp-trad
       ^-  form:tapp-trad
       (~(handle-command handler bowl app-state) u.next)
-    (take-trad ~)
+    (take-trad bowl ~)
+  ::
+  ::  Cancel outstanding contracts
+  ::
+  ++  cancel-contracts
+    |=  contracts=(set contract)
+    ^-  (quip move this-tapp)
+    [(zing (turn ~(tap in contracts) cancel-contract)) this-tapp]
+  ::
+  ::  Cancel individual contract
+  ::
+  ++  cancel-contract
+    |=  =contract
+    ^-  (list move)
+    ?-  -.contract
+      %wait  [ost.bowl %rest /(scot %da at.contract) at.contract]~
+      %hiss  ~  ::  can't cancel; will ignore response
+    ==
   --
 --
diff --git a/lib/trad.hoon b/lib/trad.hoon
index 2dedde904..36eeedf05 100644
--- a/lib/trad.hoon
+++ b/lib/trad.hoon
@@ -1,6 +1,6 @@
-|*  [input-type=mold card-type=mold]
+|*  [input-type=mold card-type=mold contract-type=mold]
 |%
-+$  trad-input  (unit input-type)
++$  trad-input  [=bowl:gall in=(unit [=wire sign=input-type])]
 +$  trad-move  (pair bone card-type)
 ::
 ::  notes:   notes to send immediately.  These will go out even if a
@@ -16,9 +16,10 @@
 ::
 ++  trad-output-raw
   |*  a=mold
-  $~  [~ ~ %done *a]
+  $~  [~ ~ ~ %done *a]
   $:  notes=(list [path card-type])
       effects=(list card-type)
+      contracts=(set [add=? contract=contract-type])
       $=  next
       $%  [%wait ~]
           [%cont self=(trad-form-raw a)]
@@ -34,7 +35,7 @@
 ++  trad-fail
   |=  err=(pair term tang)
   |=  trad-input
-  [~ ~ %fail err]
+  [~ ~ ~ %fail err]
 ::
 ++  trad
   |*  a=mold
@@ -45,7 +46,7 @@
     |=  arg=a
     ^-  form
     |=  trad-input
-    [~ ~ %done arg]
+    [~ ~ ~ %done arg]
   ::
   ++  bind
     |*  b=mold
@@ -55,7 +56,7 @@
     =/  b-res=(trad-output-raw b)
       (m-b input)
     ^-  output
-    :+  notes.b-res  effects.b-res
+    :^  notes.b-res  effects.b-res  contracts.b-res
     ?-    -.next.b-res
       %wait  [%wait ~]
       %cont  [%cont ..$(m-b self.next.b-res)]
@@ -72,6 +73,7 @@
     ::
     +$  eval-form
       $:  effects=(list card-type)
+          contracts=(set contract-type)
           =form
       ==
     ::
@@ -80,14 +82,14 @@
     ++  from-form
       |=  =form
       ^-  eval-form
-      [~ form]
+      [~ ~ form]
     ::
     ::  The cases of results of +take
     ::
     +$  eval-result
       $%  [%next ~]
-          [%fail err=(pair term tang)]
-          [%done value=a]
+          [%fail contracts=(set contract-type) err=(pair term tang)]
+          [%done contracts=(set contract-type) value=a]
       ==
     ::
     ::  Take a new sign and run the trad against it
@@ -96,8 +98,9 @@
       ::  moves: accumulate throughout recursion the moves to be
       ::         produced now
       =|  moves=(list trad-move)
-      |=  [=eval-form =bone =our=wire =trad-input]
+      |=  [=eval-form =bone =trad-input]
       ^-  [[(list trad-move) =eval-result] _eval-form]
+      =*  take-loop  $
       ::  run the trad callback
       ::
       =/  =output  (form.eval-form trad-input)
@@ -114,6 +117,33 @@
       ::
       =.  effects.eval-form
         (weld effects.eval-form effects.output)
+      ::  add or remove contracts
+      ::
+      =.  .
+        =*  loop-result  .
+        =/  new=(list [add=? contract=contract-type])
+          ~(tap in contracts.output)
+        |-  ^+  loop-result
+        =*  loop  $
+        ?~  new
+          loop-result
+        ?:  add.i.new
+          ?:  (~(has in contracts.eval-form) contract.i.new)
+            %=  loop-result
+              next.output  [%fail %contract-already-exists >contract.i.new< ~]
+            ==
+          %=  loop
+            contracts.eval-form  (~(put in contracts.eval-form) contract.i.new)
+            new                  t.new
+          ==
+        ?:  (~(has in contracts.eval-form) contract.i.new)
+          %=  loop
+            contracts.eval-form  (~(del in contracts.eval-form) contract.i.new)
+            new                  t.new
+          ==
+        %=  loop-result
+          next.output  [%fail %contract-doesnt-exist >contract.i.new< ~]
+        ==
       ::  if done, produce effects
       ::
       =?  moves  ?=(%done -.next.output)
@@ -127,14 +157,14 @@
       ::
       ?-  -.next.output
           %wait  [[moves %next ~] eval-form]
-          %fail  [[moves %fail err.next.output] eval-form]
-          %done  [[moves %done value.next.output] eval-form]
+          %fail  [[moves %fail contracts.eval-form err.next.output] eval-form]
+          %done  [[moves %done contracts.eval-form value.next.output] eval-form]
           %cont
         ::  recurse to run continuation with initialization input
         ::
-        %_  $
+        %_  take-loop
           form.eval-form  self.next.output
-          trad-input      ~
+          trad-input      [bowl.trad-input ~]
         ==
       ==
     --
diff --git a/sur/tapp.hoon b/sur/tapp.hoon
new file mode 100644
index 000000000..bbbd04651
--- /dev/null
+++ b/sur/tapp.hoon
@@ -0,0 +1,25 @@
+|%
+::
+::  Possible async calls
+::
++$  card
+  $%  [%hiss wire ~ %httr %hiss hiss:eyre]
+      [%them wire ~]
+      [%wait wire @da]
+      [%rest wire @da]
+  ==
+::
+::  Possible async responses
+::
++$  sign
+  $%  [%sigh =httr:eyre]
+      [%wake (unit tang)]
+  ==
+::
+::  Outstanding contracts
+::
++$  contract
+  $%  [%wait at=@da]
+      [%hiss ~]
+  ==
+--

From 9d1e8601e304a547540a1db490e85f64f1bece7a Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Tue, 28 May 2019 13:23:06 -0700
Subject: [PATCH 05/12] add app poking to stdio

---
 app/baby.hoon   |  6 +++++-
 app/sitter.hoon | 30 ++++++++++++++++++++++++++++++
 lib/stdio.hoon  | 21 +++++++++++++++++++++
 lib/tapp.hoon   | 16 ++++++++--------
 sur/tapp.hoon   |  2 ++
 5 files changed, 66 insertions(+), 9 deletions(-)
 create mode 100644 app/sitter.hoon

diff --git a/app/baby.hoon b/app/baby.hoon
index 850d50e26..ec0313a27 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -13,7 +13,11 @@
     $:  top-comments=(list tape)
     ==
   +$  command  cord
-  ++  tapp  (^tapp state command)
+  +$  poke-data
+    $%  [%noun cord]
+    ==
+  ++  tapp   (^tapp state command poke-data)
+  ++  stdio  (^stdio poke-data)
   --
 =>
   |%
diff --git a/app/sitter.hoon b/app/sitter.hoon
new file mode 100644
index 000000000..4e6f64514
--- /dev/null
+++ b/app/sitter.hoon
@@ -0,0 +1,30 @@
+/+  tapp, stdio
+=>
+  |%
+  +$  subscription-state
+    $:  her=ship
+        app=term
+    ==
+  +$  state
+    $:  subscription=(unit subscription-state)
+    ==
+  +$  command  cord
+  +$  poke-data
+    $%  [%noun cord]
+    ==
+  ++  tapp   (^tapp state command poke-data)
+  ++  stdio  (^stdio poke-data)
+  --
+=,  trad=trad:tapp
+=,  tapp-trad=tapp-trad:tapp
+=,  stdio
+%-  create-tapp:tapp
+^-  tapp-core:tapp
+|_  [=bowl:gall state]
+++  handle-command
+  |=  =command
+  =/  m  tapp-trad
+  ^-  form:m
+  ;<  ~  bind:m  (poke-app [our.bowl %baby] %noun 'print')
+  (pure:m subscription)
+--
diff --git a/lib/stdio.hoon b/lib/stdio.hoon
index 44fafa4da..d7bbc8d8b 100644
--- a/lib/stdio.hoon
+++ b/lib/stdio.hoon
@@ -12,6 +12,8 @@
 ::
 /-  tapp-sur=tapp
 /+  trad
+|*  poke-data=mold
+=/  tapp-sur  (tapp-sur poke-data)
 =,  card=card:tapp-sur
 =,  sign=sign:tapp-sur
 =,  contract=contract:tapp-sur
@@ -36,6 +38,15 @@
   |=  trad-input
   [~ ~ (silt [add contract]~) %done ~]
 ::
+::  Send effect
+::
+++  send-effect
+  |=  =card
+  =/  m  (trad ,~)
+  ^-  form:m
+  |=  trad-input
+  [~ [card]~ ~ %done ~]
+::
 ::    ----
 ::
 ::  HTTP requests
@@ -181,4 +192,14 @@
   ?.  ?=(%cont -.next.c-res)
     c-res
   c-res(self.next ..loop(computation self.next.c-res))
+::
+::    ----
+::
+::  Apps
+::
+++  poke-app
+  |=  [[her=ship app=term] =poke-data]
+  =/  m  (trad ,~)
+  ^-  form:m
+  (send-effect %poke / [her app] poke-data)
 --
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index 3d24b281b..e4a9001be 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -1,11 +1,11 @@
-/-  tapp
+/-  tapp-sur=tapp
 /+  trad
-=,  card=card:tapp
-=,  sign=sign:tapp
-=,  contract=contract:tapp
-=,  trad-lib=trad
-|*  [state-type=mold command-type=mold]
+|*  [state-type=mold command-type=mold poke-data=mold]
 |%
+++  tapp-sur  (^tapp-sur poke-data)
+++  card  card:tapp-sur
+++  sign  sign:tapp-sur
+++  contract  contract:tapp-sur
 ::
 ::  The form of a tapp
 ::
@@ -17,7 +17,7 @@
     *form:tapp-trad
   --
 ::
-++  trad-lib  (^trad-lib sign card contract)
+++  trad-lib  (^trad sign card contract)
 ++  trad  trad:trad-lib
 ::
 +$  move  (pair bone card)
@@ -34,7 +34,7 @@
   ++  prep
     |=  old-state=*
     ^-  (quip move _this-tapp)
-    ~&  %tapp-loaded
+    ~&  [%tapp-loaded dap.bowl]
     =/  old  ((soft tapp-state) old-state)
     ?~  old
       `this-tapp
diff --git a/sur/tapp.hoon b/sur/tapp.hoon
index bbbd04651..3e2cce9da 100644
--- a/sur/tapp.hoon
+++ b/sur/tapp.hoon
@@ -1,3 +1,4 @@
+|*  poke-data=mold
 |%
 ::
 ::  Possible async calls
@@ -7,6 +8,7 @@
       [%them wire ~]
       [%wait wire @da]
       [%rest wire @da]
+      [%poke wire dock poke-data]
   ==
 ::
 ::  Possible async responses

From 96a2baabec38f7ab096e572e7685028f2f15d4ae Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Tue, 28 May 2019 15:37:42 -0700
Subject: [PATCH 06/12] more useful +diff and +sigh

---
 sys/vane/gall.hoon | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sys/vane/gall.hoon b/sys/vane/gall.hoon
index 6728f2eb6..9aa5e8911 100644
--- a/sys/vane/gall.hoon
+++ b/sys/vane/gall.hoon
@@ -682,13 +682,18 @@
       =+  ^=  arg  ^-  vase
           %-  slop
           ?:  =(0 p.u.cug)
-            [!>(`path`+.pax) !>(cag)]
+            [!>(`path`+.pax) (ap-cage cag)]
           [!>((slag (dec p.u.cug) `path`+.pax)) q.cag]
       =^  cam  +>.$  (ap-call q.u.cug arg)
       ?^  cam
         (ap-pump:(ap-lame q.u.cug u.cam) | her pax)
       (ap-pump & her pax)
     ::
+    ++  ap-cage                                         ::  cage to tagged vase
+      |=  cag/cage
+      ^-  vase
+      (slop `vase`[[%atom %tas `p.cag] p.cag] q.cag)
+    ::
     ++  ap-pump                                         ::  update subscription
       ~/  %ap-pump
       |=  {oak/? her/ship pax/path}
@@ -1094,7 +1099,7 @@
       =+  ^=  arg  ^-  vase
           %-  slop
           ?:  =(0 p.u.cug)
-            [!>(`path`pax) !>(cag)]
+            [!>(`path`pax) (ap-cage cag)]
           [!>((slag (dec p.u.cug) `path`pax)) q.cag]
       =^  cam  +>.$  (ap-call q.u.cug arg)
       ?^  cam   (ap-lame q.u.cug u.cam)

From 40c4ea45d22ce02b36033736e580555f6da83aab Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Tue, 28 May 2019 15:38:14 -0700
Subject: [PATCH 07/12] add subscriptions to stdio

---
 app/baby.hoon   |  22 +++++--
 app/sitter.hoon |  32 ++++++++--
 lib/stdio.hoon  |  71 ++++++++++++++++++++--
 lib/tapp.hoon   | 155 +++++++++++++++++++++++++++++++++++++++++-------
 lib/trad.hoon   |  30 +++++-----
 sur/tapp.hoon   |   5 +-
 6 files changed, 261 insertions(+), 54 deletions(-)

diff --git a/app/baby.hoon b/app/baby.hoon
index ec0313a27..11081b3b5 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -16,8 +16,12 @@
   +$  poke-data
     $%  [%noun cord]
     ==
-  ++  tapp   (^tapp state command poke-data)
-  ++  stdio  (^stdio poke-data)
+  +$  out-peer-data
+    $%  [%comments (list tape)]
+    ==
+  +$  in-peer-data  ~
+  ++  tapp   (^tapp state command poke-data out-peer-data in-peer-data)
+  ++  stdio  (^stdio poke-data out-peer-data)
   --
 =>
   |%
@@ -46,8 +50,8 @@
 ::
 ::  The app
 ::
-%-  create-tapp:tapp
-^-  tapp-core:tapp
+%-  create-tapp-poke-peer:tapp
+^-  tapp-core-poke-peer:tapp
 |_  [=bowl:gall state]
 ::
 ::  Main function
@@ -84,9 +88,10 @@
   |-  ^-  form:m
   =*  loop  $
   ::
-  ::  If done, print the results
+  ::  If done, tell subscriers and print the results
   ::
   ?~  top-stories
+    ;<  ~  bind:m  (give-result /comments %comments top-comments)
     (handle-command 'print')
   ::
   ::  Else, fetch the story info
@@ -118,4 +123,11 @@
   ::
   =.  top-comments  [u.comment-text top-comments]
   loop(top-stories t.top-stories)
+::
+++  handle-peer
+  |=  =path
+  =/  m  tapp-trad
+  ^-  form:m
+  ~&  [%baby-take-peer path]
+  (pure:m top-comments)
 --
diff --git a/app/sitter.hoon b/app/sitter.hoon
index 4e6f64514..0f80cac79 100644
--- a/app/sitter.hoon
+++ b/app/sitter.hoon
@@ -2,8 +2,8 @@
 =>
   |%
   +$  subscription-state
-    $:  her=ship
-        app=term
+    $:  target=[her=ship app=term]
+        =path
     ==
   +$  state
     $:  subscription=(unit subscription-state)
@@ -12,19 +12,39 @@
   +$  poke-data
     $%  [%noun cord]
     ==
-  ++  tapp   (^tapp state command poke-data)
-  ++  stdio  (^stdio poke-data)
+  +$  out-peer-data  ~
+  +$  in-peer-data
+    $%  [%comments comments=(list tape)]
+    ==
+  ++  tapp   (^tapp state command poke-data out-peer-data in-peer-data)
+  ++  stdio  (^stdio poke-data out-peer-data)
   --
 =,  trad=trad:tapp
 =,  tapp-trad=tapp-trad:tapp
 =,  stdio
-%-  create-tapp:tapp
-^-  tapp-core:tapp
+%-  create-tapp-poke-diff:tapp
+^-  tapp-core-poke-diff:tapp
 |_  [=bowl:gall state]
 ++  handle-command
   |=  =command
   =/  m  tapp-trad
   ^-  form:m
+  ?:  =(command 'pull')
+    ?~  subscription
+      (trad-fail %no-subscription ~)
+    ;<  ~  bind:m  (pull-app [target path]:u.subscription)
+    (pure:m ~)
   ;<  ~  bind:m  (poke-app [our.bowl %baby] %noun 'print')
+  ;<  ~  bind:m  (peer-app [our.bowl %baby] /comments)
+  =.  subscription  `[[our.bowl %baby] /comments]
+  ;<  ~  bind:m  (wait (add now.bowl ~s3))
+  (pure:m subscription)
+::
+++  handle-diff
+  |=  [[her=ship app=term] =path data=in-peer-data]
+  =/  m  tapp-trad
+  ^-  form:m
+  ?>  ?=(%comments -.data)
+  ~&  sitter-got-data=(lent comments.data)
   (pure:m subscription)
 --
diff --git a/lib/stdio.hoon b/lib/stdio.hoon
index d7bbc8d8b..ea30c1192 100644
--- a/lib/stdio.hoon
+++ b/lib/stdio.hoon
@@ -1,4 +1,4 @@
-::  Standard input/input functions.
+::  Standard input/output functions.
 ::
 ::  These are all asynchronous computations, which means they produce a
 ::  form:(trad A) for some type A.  You can always tell what they
@@ -12,8 +12,8 @@
 ::
 /-  tapp-sur=tapp
 /+  trad
-|*  poke-data=mold
-=/  tapp-sur  (tapp-sur poke-data)
+|*  [poke-data=mold out-peer-data=mold]
+=/  tapp-sur  (tapp-sur poke-data out-peer-data)
 =,  card=card:tapp-sur
 =,  sign=sign:tapp-sur
 =,  contract=contract:tapp-sur
@@ -26,7 +26,7 @@
   |=  =card
   =/  m  (trad ,~)
   ^-  form:m
-  |=  trad-input
+  |=  =trad-input
   [[/ card]~ ~ ~ %done ~]
 ::
 ::  Add or remove a contract
@@ -38,14 +38,25 @@
   |=  trad-input
   [~ ~ (silt [add contract]~) %done ~]
 ::
-::  Send effect
+::  Send effect on current bone
 ::
 ++  send-effect
   |=  =card
   =/  m  (trad ,~)
   ^-  form:m
+  ;<  =bone  bind:m
+    |=  =trad-input
+    [~ ~ ~ %done ost.bowl.trad-input]
+  (send-effect-on-bone bone card)
+::
+::  Send effect on particular bone
+::
+++  send-effect-on-bone
+  |=  [=bone =card]
+  =/  m  (trad ,~)
+  ^-  form:m
   |=  trad-input
-  [~ [card]~ ~ %done ~]
+  [~ [bone card]~ ~ %done ~]
 ::
 ::    ----
 ::
@@ -202,4 +213,52 @@
   =/  m  (trad ,~)
   ^-  form:m
   (send-effect %poke / [her app] poke-data)
+::
+++  peer-app
+  |=  [[her=ship app=term] =path]
+  =/  m  (trad ,~)
+  ^-  form:m
+  =/  =wire  (weld /(scot %p her)/[app] path)
+  (send-effect %peer wire [her app] path)
+::
+++  pull-app
+  |=  [[her=ship app=term] =path]
+  =/  m  (trad ,~)
+  ^-  form:m
+  =/  =wire  (weld /(scot %p her)/[app] path)
+  (send-effect %pull wire [her app] ~)
+::
+::    ----
+::
+::  Handle subscriptions
+::
+::  Get bones at particular path; for internal use only
+::
+++  get-bones-on-path
+  |=  =the=path
+  =/  m  (trad ,(list bone))
+  ^-  form:m
+  |=  =trad-input
+  :^  ~  ~  ~
+  :-  %done
+  %+  murn  ~(tap by sup.bowl.trad-input)
+  |=  [ost=bone her=ship =sub=path]
+  ^-  (unit bone)
+  ?.  =(the-path sub-path)
+    ~
+  `ost
+::
+::  Give a result to subscribers on particular path
+::
+++  give-result
+  |=  [=path =out-peer-data]
+  =/  m  (trad ,~)
+  ^-  form:m
+  ;<  bones=(list bone)  bind:m  (get-bones-on-path path)
+  |-  ^-  form:m
+  =*  loop  $
+  ?~  bones
+    (pure:m ~)
+  ;<  ~  bind:m  (send-effect-on-bone i.bones %diff out-peer-data)
+  loop(bones t.bones)
 --
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index e4a9001be..a5716f005 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -1,21 +1,21 @@
 /-  tapp-sur=tapp
 /+  trad
-|*  [state-type=mold command-type=mold poke-data=mold]
+|*  $:  state-type=mold
+        command-type=mold
+        poke-data=mold
+        out-peer-data=mold
+        in-peer-data=mold
+    ==
 |%
-++  tapp-sur  (^tapp-sur poke-data)
+++  tapp-sur  (^tapp-sur poke-data out-peer-data)
 ++  card  card:tapp-sur
 ++  sign  sign:tapp-sur
 ++  contract  contract:tapp-sur
-::
-::  The form of a tapp
-::
-++  tapp-core
-  $_  ^|
-  |_  [bowl:gall state-type]
-  ++  handle-command
-    |~  command-type
-    *form:tapp-trad
-  --
+++  command
+  $%  [%poke command=command-type]
+      [%peer =path]
+      [%diff =dock =path =in-peer-data]
+  ==
 ::
 ++  trad-lib  (^trad sign card contract)
 ++  trad  trad:trad-lib
@@ -23,12 +23,95 @@
 +$  move  (pair bone card)
 ++  tapp-trad  (trad state-type)
 +$  tapp-state
-  $:  waiting=(qeu command-type)
+  $:  waiting=(qeu command)
       active=(unit eval-form:eval:tapp-trad)
       app-state=state-type
   ==
-++  create-tapp
-  |=  handler=tapp-core
+::
+::  The form of a tapp that only handles pokes
+::
+++  tapp-core-poke
+  $_  ^|
+  |_  [bowl:gall state-type]
+  ++  handle-command
+    |~  command-type
+    *form:tapp-trad
+  --
+::
+++  create-tapp-poke
+  |=  handler=tapp-core-poke
+  %-  create-tapp-poke-peer
+  |_  [=bowl:gall state=state-type]
+  ++  handle-command  ~(handle-command handler bowl state)
+  ++  handle-peer     |=(* (trad-fail:trad-lib %no-peer-handler >path< ~))
+  --
+::
+::  The form of a tapp that only handles pokes and peers
+::
+++  tapp-core-poke-peer
+  $_  ^|
+  |_  [bowl:gall state-type]
+  ++  handle-command
+    |~  command-type
+    *form:tapp-trad
+  ::
+  ++  handle-peer
+    |~  path
+    *form:tapp-trad
+  --
+::
+++  create-tapp-poke-peer
+  |=  handler=tapp-core-poke-peer
+  %-  create-tapp-all
+  |_  [=bowl:gall state=state-type]
+  ++  handle-command  ~(handle-command handler bowl state)
+  ++  handle-peer     ~(handle-peer handler bowl state)
+  ++  handle-diff     |=(* (trad-fail:trad-lib %no-diff-handler >path< ~))
+  --
+::
+::  The form of a tapp that only handles pokes and diffs
+::
+++  tapp-core-poke-diff
+  $_  ^|
+  |_  [bowl:gall state-type]
+  ++  handle-command
+    |~  command-type
+    *form:tapp-trad
+  ::
+  ++  handle-diff
+    |~  [dock path in-peer-data]
+    *form:tapp-trad
+  --
+::
+++  create-tapp-poke-diff
+  |=  handler=tapp-core-poke-diff
+  %-  create-tapp-all
+  |_  [=bowl:gall state=state-type]
+  ++  handle-command  ~(handle-command handler bowl state)
+  ++  handle-peer     |=(=path (trad-fail:trad-lib %no-peer-handler >path< ~))
+  ++  handle-diff     ~(handle-diff handler bowl state)
+  --
+::
+::  The form of a tapp
+::
+++  tapp-core-all
+  $_  ^|
+  |_  [bowl:gall state-type]
+  ++  handle-command
+    |~  command-type
+    *form:tapp-trad
+  ::
+  ++  handle-peer
+    |~  path
+    *form:tapp-trad
+  ::
+  ++  handle-diff
+    |~  [dock path in-peer-data]
+    *form:tapp-trad
+  --
+::
+++  create-tapp-all
+  |=  handler=tapp-core-all
   |_  [=bowl:gall tapp-state]
   ++  this-tapp  .
   ++  prep
@@ -45,12 +128,36 @@
   ++  poke-noun
     |=  command=command-type
     ^-  (quip move _this-tapp)
-    =.  waiting  (~(put to waiting) command)
+    =.  waiting  (~(put to waiting) %poke command)
     ?^  active
       ~&  [%waiting-until-current-trad-finishes waiting]
       `this-tapp
     start-trad
   ::
+  ::  Receive subscription request
+  ::
+  ++  peer
+    |=  =path
+    ^-  (quip move _this-tapp)
+    =.  waiting  (~(put to waiting) %peer path)
+    ?^  active
+      `this-tapp
+    start-trad
+  ::
+  ::  Receive subscription response
+  ::
+  ++  diff
+    |=  [=wire =in-peer-data]
+    ^-  (quip move _this-tapp)
+    ?>  ?=([@ @ *] wire)
+    =/  her  (slav %p i.wire)
+    =*  app  i.t.wire
+    =*  pax  t.t.wire
+    =.  waiting  (~(put to waiting) %diff [her app] pax in-peer-data)
+    ?^  active
+      `this-tapp
+    start-trad
+  ::
   ::  Pass response to trad
   ::
   ++  sigh-httr
@@ -106,7 +213,12 @@
   ++  fail-trad
     |=  [contracts=(set contract) err=(pair term tang)]
     ^-  (quip move _this-tapp)
-    %-  (slog leaf+"tapp command failed" leaf+(trip p.err) q.err)
+    %-  %-  slog
+        :*  leaf+(trip dap.bowl)
+            leaf+"tapp command failed"
+            leaf+(trip p.err)
+            q.err
+        ==
     (finish-trad contracts)
   ::
   ::  Called on trad success
@@ -135,15 +247,18 @@
     ^-  (quip move _this-tapp)
     ?.  =(~ active)
       ~|  %trad-already-active  !!
-    =/  next=(unit command-type)  ~(top to waiting)
+    =/  next=(unit command)  ~(top to waiting)
     ?~  next
       `this-tapp
     =.  active
       :-  ~
-      ^-  eval-form:eval:tapp-trad
       %-  from-form:eval:tapp-trad
       ^-  form:tapp-trad
-      (~(handle-command handler bowl app-state) u.next)
+      ?-  -.u.next
+        %poke  (~(handle-command handler bowl app-state) command.u.next)
+        %peer  (~(handle-peer handler bowl app-state) path.u.next)
+        %diff  (~(handle-diff handler bowl app-state) +.u.next)
+      ==
     (take-trad bowl ~)
   ::
   ::  Cancel outstanding contracts
diff --git a/lib/trad.hoon b/lib/trad.hoon
index 36eeedf05..f032896a7 100644
--- a/lib/trad.hoon
+++ b/lib/trad.hoon
@@ -3,22 +3,23 @@
 +$  trad-input  [=bowl:gall in=(unit [=wire sign=input-type])]
 +$  trad-move  (pair bone card-type)
 ::
-::  notes:   notes to send immediately.  These will go out even if a
-::           later stage of the process fails, so they shouldn't have any
-::           semantic effect on the rest of the system.  Path is
-::           included exclusively for documentation and |verb.
-::  effects: moves to send after the process ends.
-::  wait:    don't move on, stay here.  The next sign should come back
-::           to this same callback.
-::  cont:    continue process with new callback.
-::  fail:    abort process; don't send effects
-::  done:    finish process; send effects
+::  notes:     notes to send immediately.  These will go out even if a
+::             later stage of the process fails, so they shouldn't have
+::             any semantic effect on the rest of the system.  Path is
+::             included exclusively for documentation and |verb.
+::  effects:   moves to send after the process ends.
+::  contracts: stuff to cancel at end of transaction.
+::  wait:      don't move on, stay here.  The next sign should come back
+::             to this same callback.
+::  cont:      continue process with new callback.
+::  fail:      abort process; don't send effects
+::  done:      finish process; send effects
 ::
 ++  trad-output-raw
   |*  a=mold
   $~  [~ ~ ~ %done *a]
   $:  notes=(list [path card-type])
-      effects=(list card-type)
+      effects=(list trad-move)
       contracts=(set [add=? contract=contract-type])
       $=  next
       $%  [%wait ~]
@@ -72,7 +73,7 @@
     ::  Indelible state of a trad
     ::
     +$  eval-form
-      $:  effects=(list card-type)
+      $:  effects=(list trad-move)
           contracts=(set contract-type)
           =form
       ==
@@ -149,10 +150,7 @@
       =?  moves  ?=(%done -.next.output)
         %+  welp
           moves
-        %+  turn  effects.eval-form
-        |=  card=card-type
-        ^-  trad-move
-        [bone card]
+        effects.eval-form
       ::  case-wise handle next steps
       ::
       ?-  -.next.output
diff --git a/sur/tapp.hoon b/sur/tapp.hoon
index 3e2cce9da..a53cb0414 100644
--- a/sur/tapp.hoon
+++ b/sur/tapp.hoon
@@ -1,4 +1,4 @@
-|*  poke-data=mold
+|*  [poke-data=mold out-peer-data=mold]
 |%
 ::
 ::  Possible async calls
@@ -9,6 +9,9 @@
       [%wait wire @da]
       [%rest wire @da]
       [%poke wire dock poke-data]
+      [%peer wire dock path]
+      [%pull wire dock ~]
+      [%diff out-peer-data]
   ==
 ::
 ::  Possible async responses

From 4c93a6f6e952e1ea79eebe616b30ab97c0469c73 Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Tue, 28 May 2019 16:06:53 -0700
Subject: [PATCH 08/12] generalize poke in lib/tapp

---
 app/baby.hoon   | 6 +++---
 app/sitter.hoon | 4 ++--
 lib/tapp.hoon   | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/app/baby.hoon b/app/baby.hoon
index 11081b3b5..a6d99c5a1 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -12,7 +12,7 @@
   +$  state
     $:  top-comments=(list tape)
     ==
-  +$  command  cord
+  +$  command  [%noun =cord]
   +$  poke-data
     $%  [%noun cord]
     ==
@@ -63,7 +63,7 @@
   ::
   ::  If requested to print, just print what we have in our state
   ::
-  ?:  =(command 'print')
+  ?:  =(cord.command 'print')
     ~&  'drumroll please...'
     ;<  now=@da  bind:m  get-time
     ;<  ~        bind:m  (wait (add now ~s3))
@@ -92,7 +92,7 @@
   ::
   ?~  top-stories
     ;<  ~  bind:m  (give-result /comments %comments top-comments)
-    (handle-command 'print')
+    (handle-command %noun 'print')
   ::
   ::  Else, fetch the story info
   ::
diff --git a/app/sitter.hoon b/app/sitter.hoon
index 0f80cac79..625d16a20 100644
--- a/app/sitter.hoon
+++ b/app/sitter.hoon
@@ -8,7 +8,7 @@
   +$  state
     $:  subscription=(unit subscription-state)
     ==
-  +$  command  cord
+  +$  command  [%noun =cord]
   +$  poke-data
     $%  [%noun cord]
     ==
@@ -29,7 +29,7 @@
   |=  =command
   =/  m  tapp-trad
   ^-  form:m
-  ?:  =(command 'pull')
+  ?:  =(cord.command 'pull')
     ?~  subscription
       (trad-fail %no-subscription ~)
     ;<  ~  bind:m  (pull-app [target path]:u.subscription)
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index a5716f005..43a60b4d1 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -125,7 +125,7 @@
   ::
   ::  Start a command
   ::
-  ++  poke-noun
+  ++  poke
     |=  command=command-type
     ^-  (quip move _this-tapp)
     =.  waiting  (~(put to waiting) %poke command)

From c48f9422641bdae715b9fb5e0b1484be73176d28 Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Tue, 28 May 2019 17:01:18 -0700
Subject: [PATCH 09/12] add effectful timers

---
 app/baby.hoon  | 16 +++++++++++--
 lib/stdio.hoon | 10 +++++++-
 lib/tapp.hoon  | 65 ++++++++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 84 insertions(+), 7 deletions(-)

diff --git a/app/baby.hoon b/app/baby.hoon
index a6d99c5a1..02111e375 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -50,8 +50,8 @@
 ::
 ::  The app
 ::
-%-  create-tapp-poke-peer:tapp
-^-  tapp-core-poke-peer:tapp
+%-  create-tapp-poke-peer-take:tapp
+^-  tapp-core-poke-peer-take:tapp
 |_  [=bowl:gall state]
 ::
 ::  Main function
@@ -70,6 +70,9 @@
     ~&  'Top comments:'
     %-  (slog (zing (turn top-comments comment-to-tang)))
     (pure:m top-comments)
+  ?:  =(cord.command 'poll')
+    ;<  ~  bind:m  (wait-effect (add now.bowl ~s15))
+    (pure:m top-comments)
   ::
   ::  Otherwise, fetch the top HN stories
   ::
@@ -130,4 +133,13 @@
   ^-  form:m
   ~&  [%baby-take-peer path]
   (pure:m top-comments)
+::
+++  handle-take
+  |=  sign:tapp
+  =/  m  tapp-trad
+  ^-  form:m
+  ;<  =state  bind:m  (handle-command %noun 'fetch')
+  =.  top-comments  state
+  (pure:m top-comments)
+  ::  (handle-command %noun 'poll')
 --
diff --git a/lib/stdio.hoon b/lib/stdio.hoon
index ea30c1192..459dd2912 100644
--- a/lib/stdio.hoon
+++ b/lib/stdio.hoon
@@ -147,7 +147,7 @@
   |=  at=@da
   =/  m  (trad ,~)
   ^-  form:m
-  ;<  ~  bind:m  (send-raw-card %wait /(scot %da at) at)
+  ;<  ~  bind:m  (send-raw-card %wait /note/(scot %da at) at)
   (set-raw-contract & %wait at)
 ::
 ::  Wait until we get a wake event
@@ -185,6 +185,14 @@
   ;<  ~  bind:m  (send-wait until)
   take-wake
 ::
+::  Wait until time then start new computation
+::
+++  wait-effect
+  |=  until=@da
+  =/  m  (trad ,~)
+  ^-  form:m
+  (send-effect %wait /effect/(scot %da until) until)
+::
 ::  Cancel computation if not done by time
 ::
 ++  set-timeout
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index 43a60b4d1..553e490c8 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -15,6 +15,7 @@
   $%  [%poke command=command-type]
       [%peer =path]
       [%diff =dock =path =in-peer-data]
+      [%take =sign]
   ==
 ::
 ++  trad-lib  (^trad sign card contract)
@@ -67,6 +68,7 @@
   ++  handle-command  ~(handle-command handler bowl state)
   ++  handle-peer     ~(handle-peer handler bowl state)
   ++  handle-diff     |=(* (trad-fail:trad-lib %no-diff-handler >path< ~))
+  ++  handle-take     |=(* (trad-fail:trad-lib %no-take-handler >path< ~))
   --
 ::
 ::  The form of a tapp that only handles pokes and diffs
@@ -88,8 +90,37 @@
   %-  create-tapp-all
   |_  [=bowl:gall state=state-type]
   ++  handle-command  ~(handle-command handler bowl state)
-  ++  handle-peer     |=(=path (trad-fail:trad-lib %no-peer-handler >path< ~))
+  ++  handle-peer     |=(* (trad-fail:trad-lib %no-peer-handler >path< ~))
   ++  handle-diff     ~(handle-diff handler bowl state)
+  ++  handle-take     |=(* (trad-fail:trad-lib %no-take-handler >path< ~))
+  --
+::
+::  The form of a tapp that only handles pokes, peers, and takes
+::
+++  tapp-core-poke-peer-take
+  $_  ^|
+  |_  [bowl:gall state-type]
+  ++  handle-command
+    |~  command-type
+    *form:tapp-trad
+  ::
+  ++  handle-peer
+    |~  path
+    *form:tapp-trad
+  ::
+  ++  handle-take
+    |~  sign
+    *form:tapp-trad
+  --
+::
+++  create-tapp-poke-peer-take
+  |=  handler=tapp-core-poke-peer-take
+  %-  create-tapp-all
+  |_  [=bowl:gall state=state-type]
+  ++  handle-command  ~(handle-command handler bowl state)
+  ++  handle-peer     ~(handle-peer handler bowl state)
+  ++  handle-diff     |=(* (trad-fail:trad-lib %no-diff-handler >path< ~))
+  ++  handle-take     ~(handle-take handler bowl state)
   --
 ::
 ::  The form of a tapp
@@ -97,17 +128,30 @@
 ++  tapp-core-all
   $_  ^|
   |_  [bowl:gall state-type]
+  ::
+  ::  Input
+  ::
   ++  handle-command
     |~  command-type
     *form:tapp-trad
   ::
+  ::  Subscription request
+  ::
   ++  handle-peer
     |~  path
     *form:tapp-trad
   ::
+  ::  Receive subscription result
+  ::
   ++  handle-diff
     |~  [dock path in-peer-data]
     *form:tapp-trad
+  ::
+  ::  Receive syscall result
+  ::
+  ++  handle-take
+    |~  sign
+    *form:tapp-trad
   --
 ::
 ++  create-tapp-all
@@ -172,13 +216,21 @@
     ^-  (quip move _this-tapp)
     (oob-fail-trad %failed-sigh tang)
   ::
-  ++  wake
+  ++  wake-note
     |=  [=wire error=(unit tang)]
     ^-  (quip move _this-tapp)
     ?^  error
       (oob-fail-trad %timer-fire-failed u.error)
     (take-trad bowl `[wire %wake ~])
   ::
+  ++  wake-effect
+    |=  [=wire error=(unit tang)]
+    ^-  (quip move _this-tapp)
+    =.  waiting  (~(put to waiting) %take %wake error)
+    ?^  active
+      `this-tapp
+    start-trad
+  ::
   ::  Continue computing trad
   ::
   ++  take-trad
@@ -191,7 +243,11 @@
       ::
       ?:  ?=([~ @ %sigh *] in.trad-input)
         `this-tapp
-      ~|  %no-active-trad  !!
+      ~|  %no-active-trad
+      ~|  ?~  in.trad-input
+            ~
+          wire.u.in.trad-input
+      !!
     =^  r=[moves=(list move) =eval-result:eval:m]  u.active
       (take:eval:m u.active ost.bowl trad-input)
     =>  .(active `(unit eval-form:eval:tapp-trad)`active)  :: TMI
@@ -258,6 +314,7 @@
         %poke  (~(handle-command handler bowl app-state) command.u.next)
         %peer  (~(handle-peer handler bowl app-state) path.u.next)
         %diff  (~(handle-diff handler bowl app-state) +.u.next)
+        %take  (~(handle-take handler bowl app-state) +.u.next)
       ==
     (take-trad bowl ~)
   ::
@@ -274,7 +331,7 @@
     |=  =contract
     ^-  (list move)
     ?-  -.contract
-      %wait  [ost.bowl %rest /(scot %da at.contract) at.contract]~
+      %wait  [ost.bowl %rest /note/(scot %da at.contract) at.contract]~
       %hiss  ~  ::  can't cancel; will ignore response
     ==
   --

From 87e50458fc99e2f1af446b9a6197b7a912a76df3 Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Tue, 28 May 2019 17:11:21 -0700
Subject: [PATCH 10/12] rename command -> poke

---
 app/baby.hoon   | 26 +++++++++----------
 app/sitter.hoon | 16 ++++++------
 lib/tapp.hoon   | 67 ++++++++++++++++++++++++-------------------------
 3 files changed, 52 insertions(+), 57 deletions(-)

diff --git a/app/baby.hoon b/app/baby.hoon
index 02111e375..c01cc4b58 100644
--- a/app/baby.hoon
+++ b/app/baby.hoon
@@ -12,16 +12,14 @@
   +$  state
     $:  top-comments=(list tape)
     ==
-  +$  command  [%noun =cord]
-  +$  poke-data
-    $%  [%noun cord]
-    ==
+  +$  in-poke-data   [%noun =cord]
+  +$  out-poke-data  ~
+  +$  in-peer-data   ~
   +$  out-peer-data
     $%  [%comments (list tape)]
     ==
-  +$  in-peer-data  ~
-  ++  tapp   (^tapp state command poke-data out-peer-data in-peer-data)
-  ++  stdio  (^stdio poke-data out-peer-data)
+  ++  tapp   (^tapp state in-poke-data out-poke-data in-peer-data out-peer-data)
+  ++  stdio  (^stdio out-poke-data out-peer-data)
   --
 =>
   |%
@@ -56,21 +54,21 @@
 ::
 ::  Main function
 ::
-++  handle-command
-  |=  =command
+++  handle-poke
+  |=  =in-poke-data
   =/  m  tapp-trad
   ^-  form:m
   ::
   ::  If requested to print, just print what we have in our state
   ::
-  ?:  =(cord.command 'print')
+  ?:  =(cord.in-poke-data 'print')
     ~&  'drumroll please...'
     ;<  now=@da  bind:m  get-time
     ;<  ~        bind:m  (wait (add now ~s3))
     ~&  'Top comments:'
     %-  (slog (zing (turn top-comments comment-to-tang)))
     (pure:m top-comments)
-  ?:  =(cord.command 'poll')
+  ?:  =(cord.in-poke-data 'poll')
     ;<  ~  bind:m  (wait-effect (add now.bowl ~s15))
     (pure:m top-comments)
   ::
@@ -95,7 +93,7 @@
   ::
   ?~  top-stories
     ;<  ~  bind:m  (give-result /comments %comments top-comments)
-    (handle-command %noun 'print')
+    (handle-poke %noun 'print')
   ::
   ::  Else, fetch the story info
   ::
@@ -138,8 +136,8 @@
   |=  sign:tapp
   =/  m  tapp-trad
   ^-  form:m
-  ;<  =state  bind:m  (handle-command %noun 'fetch')
+  ;<  =state  bind:m  (handle-poke %noun 'fetch')
   =.  top-comments  state
   (pure:m top-comments)
-  ::  (handle-command %noun 'poll')
+  ::  (handle-poke %noun 'poll')
 --
diff --git a/app/sitter.hoon b/app/sitter.hoon
index 625d16a20..242899bd3 100644
--- a/app/sitter.hoon
+++ b/app/sitter.hoon
@@ -8,16 +8,14 @@
   +$  state
     $:  subscription=(unit subscription-state)
     ==
-  +$  command  [%noun =cord]
-  +$  poke-data
-    $%  [%noun cord]
-    ==
+  +$  in-poke-data   [%noun =cord]
+  +$  out-poke-data  [%noun =cord]
   +$  out-peer-data  ~
   +$  in-peer-data
     $%  [%comments comments=(list tape)]
     ==
-  ++  tapp   (^tapp state command poke-data out-peer-data in-peer-data)
-  ++  stdio  (^stdio poke-data out-peer-data)
+  ++  tapp   (^tapp state in-poke-data out-poke-data in-peer-data out-peer-data)
+  ++  stdio  (^stdio out-poke-data out-peer-data)
   --
 =,  trad=trad:tapp
 =,  tapp-trad=tapp-trad:tapp
@@ -25,11 +23,11 @@
 %-  create-tapp-poke-diff:tapp
 ^-  tapp-core-poke-diff:tapp
 |_  [=bowl:gall state]
-++  handle-command
-  |=  =command
+++  handle-poke
+  |=  =in-poke-data
   =/  m  tapp-trad
   ^-  form:m
-  ?:  =(cord.command 'pull')
+  ?:  =(cord.in-poke-data 'pull')
     ?~  subscription
       (trad-fail %no-subscription ~)
     ;<  ~  bind:m  (pull-app [target path]:u.subscription)
diff --git a/lib/tapp.hoon b/lib/tapp.hoon
index 553e490c8..b97fa4295 100644
--- a/lib/tapp.hoon
+++ b/lib/tapp.hoon
@@ -1,18 +1,18 @@
 /-  tapp-sur=tapp
 /+  trad
 |*  $:  state-type=mold
-        command-type=mold
-        poke-data=mold
-        out-peer-data=mold
+        in-poke-data=mold
+        out-poke-data=mold
         in-peer-data=mold
+        out-peer-data=mold
     ==
 |%
-++  tapp-sur  (^tapp-sur poke-data out-peer-data)
+++  tapp-sur  (^tapp-sur out-poke-data out-peer-data)
 ++  card  card:tapp-sur
 ++  sign  sign:tapp-sur
 ++  contract  contract:tapp-sur
 ++  command
-  $%  [%poke command=command-type]
+  $%  [%poke =in-poke-data]
       [%peer =path]
       [%diff =dock =path =in-peer-data]
       [%take =sign]
@@ -34,8 +34,8 @@
 ++  tapp-core-poke
   $_  ^|
   |_  [bowl:gall state-type]
-  ++  handle-command
-    |~  command-type
+  ++  handle-poke
+    |~  in-poke-data
     *form:tapp-trad
   --
 ::
@@ -43,8 +43,8 @@
   |=  handler=tapp-core-poke
   %-  create-tapp-poke-peer
   |_  [=bowl:gall state=state-type]
-  ++  handle-command  ~(handle-command handler bowl state)
-  ++  handle-peer     |=(* (trad-fail:trad-lib %no-peer-handler >path< ~))
+  ++  handle-poke  ~(handle-poke handler bowl state)
+  ++  handle-peer  |=(* (trad-fail:trad-lib %no-peer-handler >path< ~))
   --
 ::
 ::  The form of a tapp that only handles pokes and peers
@@ -52,8 +52,8 @@
 ++  tapp-core-poke-peer
   $_  ^|
   |_  [bowl:gall state-type]
-  ++  handle-command
-    |~  command-type
+  ++  handle-poke
+    |~  in-poke-data
     *form:tapp-trad
   ::
   ++  handle-peer
@@ -65,10 +65,10 @@
   |=  handler=tapp-core-poke-peer
   %-  create-tapp-all
   |_  [=bowl:gall state=state-type]
-  ++  handle-command  ~(handle-command handler bowl state)
-  ++  handle-peer     ~(handle-peer handler bowl state)
-  ++  handle-diff     |=(* (trad-fail:trad-lib %no-diff-handler >path< ~))
-  ++  handle-take     |=(* (trad-fail:trad-lib %no-take-handler >path< ~))
+  ++  handle-poke  ~(handle-poke handler bowl state)
+  ++  handle-peer  ~(handle-peer handler bowl state)
+  ++  handle-diff  |=(* (trad-fail:trad-lib %no-diff-handler >path< ~))
+  ++  handle-take  |=(* (trad-fail:trad-lib %no-take-handler >path< ~))
   --
 ::
 ::  The form of a tapp that only handles pokes and diffs
@@ -76,8 +76,8 @@
 ++  tapp-core-poke-diff
   $_  ^|
   |_  [bowl:gall state-type]
-  ++  handle-command
-    |~  command-type
+  ++  handle-poke
+    |~  in-poke-data
     *form:tapp-trad
   ::
   ++  handle-diff
@@ -89,10 +89,10 @@
   |=  handler=tapp-core-poke-diff
   %-  create-tapp-all
   |_  [=bowl:gall state=state-type]
-  ++  handle-command  ~(handle-command handler bowl state)
-  ++  handle-peer     |=(* (trad-fail:trad-lib %no-peer-handler >path< ~))
-  ++  handle-diff     ~(handle-diff handler bowl state)
-  ++  handle-take     |=(* (trad-fail:trad-lib %no-take-handler >path< ~))
+  ++  handle-poke  ~(handle-poke handler bowl state)
+  ++  handle-peer  |=(* (trad-fail:trad-lib %no-peer-handler >path< ~))
+  ++  handle-diff  ~(handle-diff handler bowl state)
+  ++  handle-take  |=(* (trad-fail:trad-lib %no-take-handler >path< ~))
   --
 ::
 ::  The form of a tapp that only handles pokes, peers, and takes
@@ -100,8 +100,8 @@
 ++  tapp-core-poke-peer-take
   $_  ^|
   |_  [bowl:gall state-type]
-  ++  handle-command
-    |~  command-type
+  ++  handle-poke
+    |~  in-poke-data
     *form:tapp-trad
   ::
   ++  handle-peer
@@ -117,10 +117,10 @@
   |=  handler=tapp-core-poke-peer-take
   %-  create-tapp-all
   |_  [=bowl:gall state=state-type]
-  ++  handle-command  ~(handle-command handler bowl state)
-  ++  handle-peer     ~(handle-peer handler bowl state)
-  ++  handle-diff     |=(* (trad-fail:trad-lib %no-diff-handler >path< ~))
-  ++  handle-take     ~(handle-take handler bowl state)
+  ++  handle-poke  ~(handle-poke handler bowl state)
+  ++  handle-peer  ~(handle-peer handler bowl state)
+  ++  handle-diff  |=(* (trad-fail:trad-lib %no-diff-handler >path< ~))
+  ++  handle-take  ~(handle-take handler bowl state)
   --
 ::
 ::  The form of a tapp
@@ -131,8 +131,8 @@
   ::
   ::  Input
   ::
-  ++  handle-command
-    |~  command-type
+  ++  handle-poke
+    |~  in-poke-data
     *form:tapp-trad
   ::
   ::  Subscription request
@@ -170,9 +170,9 @@
   ::  Start a command
   ::
   ++  poke
-    |=  command=command-type
+    |=  =in-poke-data
     ^-  (quip move _this-tapp)
-    =.  waiting  (~(put to waiting) %poke command)
+    =.  waiting  (~(put to waiting) %poke in-poke-data)
     ?^  active
       ~&  [%waiting-until-current-trad-finishes waiting]
       `this-tapp
@@ -296,7 +296,6 @@
     =^  moves-2  this-tapp  start-trad
     [(weld moves-1 moves-2) this-tapp]
   ::
-  ::
   ::  Try to start next command
   ::
   ++  start-trad
@@ -311,8 +310,8 @@
       %-  from-form:eval:tapp-trad
       ^-  form:tapp-trad
       ?-  -.u.next
-        %poke  (~(handle-command handler bowl app-state) command.u.next)
-        %peer  (~(handle-peer handler bowl app-state) path.u.next)
+        %poke  (~(handle-poke handler bowl app-state) +.u.next)
+        %peer  (~(handle-peer handler bowl app-state) +.u.next)
         %diff  (~(handle-diff handler bowl app-state) +.u.next)
         %take  (~(handle-take handler bowl app-state) +.u.next)
       ==

From b7d5d52315de2d8a4f2b7b380af9bd8a01861ef5 Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Thu, 30 May 2019 10:24:52 -0700
Subject: [PATCH 11/12] rename apps

---
 app/{baby.hoon => example-tapp-fetch.hoon}       | 2 +-
 app/{sitter.hoon => example-tapp-subscribe.hoon} | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)
 rename app/{baby.hoon => example-tapp-fetch.hoon} (99%)
 rename app/{sitter.hoon => example-tapp-subscribe.hoon} (80%)

diff --git a/app/baby.hoon b/app/example-tapp-fetch.hoon
similarity index 99%
rename from app/baby.hoon
rename to app/example-tapp-fetch.hoon
index c01cc4b58..80dd837c2 100644
--- a/app/baby.hoon
+++ b/app/example-tapp-fetch.hoon
@@ -129,7 +129,7 @@
   |=  =path
   =/  m  tapp-trad
   ^-  form:m
-  ~&  [%baby-take-peer path]
+  ~&  [%tapp-fetch-take-peer path]
   (pure:m top-comments)
 ::
 ++  handle-take
diff --git a/app/sitter.hoon b/app/example-tapp-subscribe.hoon
similarity index 80%
rename from app/sitter.hoon
rename to app/example-tapp-subscribe.hoon
index 242899bd3..b6510dd1c 100644
--- a/app/sitter.hoon
+++ b/app/example-tapp-subscribe.hoon
@@ -32,9 +32,9 @@
       (trad-fail %no-subscription ~)
     ;<  ~  bind:m  (pull-app [target path]:u.subscription)
     (pure:m ~)
-  ;<  ~  bind:m  (poke-app [our.bowl %baby] %noun 'print')
-  ;<  ~  bind:m  (peer-app [our.bowl %baby] /comments)
-  =.  subscription  `[[our.bowl %baby] /comments]
+  ;<  ~  bind:m  (poke-app [our.bowl %example-tapp-fetch] %noun 'print')
+  ;<  ~  bind:m  (peer-app [our.bowl %example-tapp-fetch] /comments)
+  =.  subscription  `[[our.bowl %example-tapp-fetch] /comments]
   ;<  ~  bind:m  (wait (add now.bowl ~s3))
   (pure:m subscription)
 ::
@@ -43,6 +43,6 @@
   =/  m  tapp-trad
   ^-  form:m
   ?>  ?=(%comments -.data)
-  ~&  sitter-got-data=(lent comments.data)
+  ~&  subscriber-got-data=(lent comments.data)
   (pure:m subscription)
 --

From 852e74cb51c55ca9ff98c97f810aee4641a0c194 Mon Sep 17 00:00:00 2001
From: Philip Monk <phil@pcmonk.me>
Date: Thu, 30 May 2019 14:43:27 -0700
Subject: [PATCH 12/12] fix fang's suggestions

---
 app/example-tapp-fetch.hoon     |  5 ++--
 app/example-tapp-subscribe.hoon |  7 ++---
 lib/stdio.hoon                  |  2 +-
 lib/trad.hoon                   | 48 +++++++++++++++++++++++----------
 4 files changed, 41 insertions(+), 21 deletions(-)

diff --git a/app/example-tapp-fetch.hoon b/app/example-tapp-fetch.hoon
index 80dd837c2..f44abdae6 100644
--- a/app/example-tapp-fetch.hoon
+++ b/app/example-tapp-fetch.hoon
@@ -41,7 +41,7 @@
     :*  top-stories=(weld base "topstories.json")
         item=|=(item=@ud `tape`:(welp base "item/" +>:(scow %ui item) ".json"))
     ==
---
+  --
 =,  trad=trad:tapp
 =,  tapp-trad=tapp-trad:tapp
 =,  stdio
@@ -89,7 +89,7 @@
   |-  ^-  form:m
   =*  loop  $
   ::
-  ::  If done, tell subscriers and print the results
+  ::  If done, tell subscribers and print the results
   ::
   ?~  top-stories
     ;<  ~  bind:m  (give-result /comments %comments top-comments)
@@ -139,5 +139,4 @@
   ;<  =state  bind:m  (handle-poke %noun 'fetch')
   =.  top-comments  state
   (pure:m top-comments)
-  ::  (handle-poke %noun 'poll')
 --
diff --git a/app/example-tapp-subscribe.hoon b/app/example-tapp-subscribe.hoon
index b6510dd1c..68901f95b 100644
--- a/app/example-tapp-subscribe.hoon
+++ b/app/example-tapp-subscribe.hoon
@@ -32,9 +32,10 @@
       (trad-fail %no-subscription ~)
     ;<  ~  bind:m  (pull-app [target path]:u.subscription)
     (pure:m ~)
-  ;<  ~  bind:m  (poke-app [our.bowl %example-tapp-fetch] %noun 'print')
-  ;<  ~  bind:m  (peer-app [our.bowl %example-tapp-fetch] /comments)
-  =.  subscription  `[[our.bowl %example-tapp-fetch] /comments]
+  =/  target  [our.bowl %example-tapp-fetch]
+  ;<  ~  bind:m  (poke-app target %noun 'print')
+  ;<  ~  bind:m  (peer-app target /comments)
+  =.  subscription  `[target /comments]
   ;<  ~  bind:m  (wait (add now.bowl ~s3))
   (pure:m subscription)
 ::
diff --git a/lib/stdio.hoon b/lib/stdio.hoon
index 459dd2912..6a631979a 100644
--- a/lib/stdio.hoon
+++ b/lib/stdio.hoon
@@ -27,7 +27,7 @@
   =/  m  (trad ,~)
   ^-  form:m
   |=  =trad-input
-  [[/ card]~ ~ ~ %done ~]
+  [[card]~ ~ ~ %done ~]
 ::
 ::  Add or remove a contract
 ::
diff --git a/lib/trad.hoon b/lib/trad.hoon
index f032896a7..f058e6043 100644
--- a/lib/trad.hoon
+++ b/lib/trad.hoon
@@ -3,22 +3,24 @@
 +$  trad-input  [=bowl:gall in=(unit [=wire sign=input-type])]
 +$  trad-move  (pair bone card-type)
 ::
-::  notes:     notes to send immediately.  These will go out even if a
-::             later stage of the process fails, so they shouldn't have
-::             any semantic effect on the rest of the system.  Path is
-::             included exclusively for documentation and |verb.
-::  effects:   moves to send after the process ends.
-::  contracts: stuff to cancel at end of transaction.
+::  cards:     cards to send immediately.  These will go out even if a
+::             later stage of the computation fails, so they shouldn't have
+::             any semantic effect on the rest of the system.
+::             Alternately, they may record an entry in contracts with
+::             enough information to undo the effect if the computation
+::             fails.
+::  effects:   moves to send after the computation ends.
+::  contracts: stuff to cancel at end of computation.
 ::  wait:      don't move on, stay here.  The next sign should come back
 ::             to this same callback.
-::  cont:      continue process with new callback.
-::  fail:      abort process; don't send effects
-::  done:      finish process; send effects
+::  cont:      continue computation with new callback.
+::  fail:      abort computation; don't send effects
+::  done:      finish computation; send effects
 ::
 ++  trad-output-raw
   |*  a=mold
   $~  [~ ~ ~ %done *a]
-  $:  notes=(list [path card-type])
+  $:  cards=(list card-type)
       effects=(list trad-move)
       contracts=(set [add=? contract=contract-type])
       $=  next
@@ -33,22 +35,40 @@
   |*  a=mold
   $-(trad-input (trad-output-raw a))
 ::
+::  Abort asynchronous computation with error message
+::
 ++  trad-fail
   |=  err=(pair term tang)
   |=  trad-input
   [~ ~ ~ %fail err]
 ::
+::  Asynchronous transcaction monad.
+::
+::  Combo of four monads:
+::  - Reader on input-type
+::  - Writer on card-type
+::  - Continuation
+::  - Exception
+::
 ++  trad
   |*  a=mold
   |%
   ++  output  (trad-output-raw a)
+  ::
+  ::  Type of an asynchronous computation.
+  ::
   ++  form  (trad-form-raw a)
+  ::
+  ::  Monadic pure.  Identity computation for bind.
+  ::
   ++  pure
     |=  arg=a
     ^-  form
     |=  trad-input
     [~ ~ ~ %done arg]
   ::
+  ::  Monadic bind.  Combines two computations, associatively.
+  ::
   ++  bind
     |*  b=mold
     |=  [m-b=(trad-form-raw b) fun=$-(b form)]
@@ -57,7 +77,7 @@
     =/  b-res=(trad-output-raw b)
       (m-b input)
     ^-  output
-    :^  notes.b-res  effects.b-res  contracts.b-res
+    :^  cards.b-res  effects.b-res  contracts.b-res
     ?-    -.next.b-res
       %wait  [%wait ~]
       %cont  [%cont ..$(m-b self.next.b-res)]
@@ -105,13 +125,13 @@
       ::  run the trad callback
       ::
       =/  =output  (form.eval-form trad-input)
-      ::  add notes to moves
+      ::  add cards to moves
       ::
       =.  moves
         %+  welp
           moves
-        %+  turn  notes.output
-        |=  [=path card=card-type]
+        %+  turn  cards.output
+        |=  card=card-type
         ^-  trad-move
         [bone card]
       ::  add effects to list to be produced when done