Add map-hyseq

NEWS.rst

@@ -3,6 +3,10 @@
 Unreleased
 ======================================================
 
+New Features
+------------------------------
+* New macro `map-hyseq`.
+
 Bug Fixes
 ------------------------------
 * `map-model` now calls `as-model` only once (before its own recursion),

docs/index.rst

@@ -104,6 +104,7 @@ API
 .. hy:automacro:: defmacro-kwargs
 .. hy:automacro:: defmacro!
 .. hy:autofunction:: macroexpand-all
+.. hy:autofunction:: map-hyseq
 .. hy:autofunction:: map-model
 .. hy:autofunction:: match-fn-params
 .. hy:automacro:: with-gensyms

hyrule/macrotools.hy

@@ -270,21 +270,34 @@
   (_map-model (hy.as-model x) f))
 
 (defn _map-model [x f]
-  (cond
-    (is-not (setx value (f x)) None)
-      (hy.as-model value)
-    (isinstance x hy.models.Sequence)
-      ((type x)
-        (gfor  elem x  (_map-model elem f))
-        #** (cond
-          (isinstance x hy.models.FString)
-            {"brackets" x.brackets}
-          (isinstance x hy.models.FComponent)
-            {"conversion" x.conversion}
-          True
-            {}))
-    True
-      x))
+  (if (is-not (setx value (f x)) None)
+    (hy.as-model value)
+    (map-hyseq x (fn [contents]
+      (gfor  elem contents  (_map-model elem f))))))
+
+(defn map-hyseq [x f]
+
+  "Apply the function ``f`` to the contents of the :ref:`sequential model <hy:hysequence>` ``x`` gathered into a tuple. ``f`` should return an iterable object. This result is then wrapped in the original model type, preserving attributes such as the brackets of an :class:`hy.models.FString`. ::
+
+    (map-hyseq '[:a :b :c] (fn [x]
+      (gfor  e x  (hy.models.Keyword (.upper e.name)))))
+      ; => '[:A :B :C]
+
+  Unlike :hy:func:`map-model`, ``map-hyseq`` isn't inherently recursive.
+
+  If ``x`` isn't a sequential Hy model, it's returned as-is, without calling ``f``."
+
+  (if (isinstance x hy.models.Sequence)
+    ((type x)
+      (f (tuple x))
+      #** (cond
+        (isinstance x hy.models.FString)
+          {"brackets" x.brackets}
+        (isinstance x hy.models.FComponent)
+          {"conversion" x.conversion}
+        True
+          {}))
+    x))
 
 
 (defmacro with-gensyms [args #* body]

tests/test_macrotools.hy

@@ -3,7 +3,7 @@
          :readers [/])
 (import
   pytest
-  hyrule [macroexpand-all map-model match-fn-params])
+  hyrule [macroexpand-all map-hyseq map-model match-fn-params])
 
 
 (defn test-defmacro-kwargs []
@@ -110,6 +110,42 @@
              '(setv blah 1))))
 
 
+(defn test-map-hyseq []
+
+  ; If `x` isn't sequential (or not a model at all), `f` isn't called.
+  (assert (=
+    (map-hyseq
+      3
+      (fn [x] (raise ValueError)))
+    3))
+  (assert (=
+    (map-hyseq
+      [1 2]
+      (fn [x] (raise ValueError)))
+    [1 2]))
+
+  ; `f` can be called when `x` is empty.
+  (assert (=
+    (map-hyseq
+      '[]
+      (fn [x] ['4]))
+    '[4]))
+
+  ; `f` gets the sequence contents as a tuple.
+  (setv saw None)
+  (assert (=
+    (map-hyseq
+      '{1 2  3 4}
+      (fn [x]
+        (nonlocal saw)
+        (setv saw x)
+        (gfor  e x  (hy.models.Integer (+ e 1)))))
+    '{2 3  4 5}))
+  (assert (= saw #('1 '2 '3 '4))))
+  ; Preservation of sequence attributes is tested as part of testing
+  ; `map-model`.
+
+
 (defn test-map-model []
 
   ; When the callback returns `None`, the element is recursed into, or