Initial version

.gitignore

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+*~
+.curry
+.cpm

LICENSE

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+Copyright (c) 2017, Sandra Dylus, Jan Christiansen, Finn Teegen
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+3. Neither the names of the copyright holders nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+pflp
+====
+
+This package provides a library for probabilistic function logic programming.

package.json

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+{
+  "name": "pflp",
+  "version": "1.0.0",
+  "author": "Sandra Dylus <[email protected]>, Jan Christiansen <[email protected]>, Finn Teegen <[email protected]>",
+  "maintainer": "Finn Teegen <[email protected]>",
+  "synopsis": "Library for Probabilistic Functional Logic Programming",
+  "category": [ "Programming" ],
+  "license": "BSD-3-Clause",
+  "licenseFile": "LICENSE",
+  "sourceDirs" : [ "src" ],
+  "exportedModules": [ "PFLP" ],
+  "dependencies": {
+  },
+  "compilerCompatibility": {
+    "kics2": "< 2.0.0",
+    "pakcs": "< 2.0.0"
+  },
+  "source": {
+    "git": "https://github.com/finnteegen/pflp.git",
+    "tag": "$version"
+  }
+}

src/PFLP.curry

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+--- Library for Probabilistic Functional Logic Programming
+--- @author Sandra Dylus, Jan Christiansen, Finn Teegen
+--- @version October 2017
+
+module PFLP
+  ( Probability
+  , Dist
+  , enum
+  , uniform
+  , certainly
+  , (>>>=)
+  , joinWith
+  , (??)
+  , RT
+  , pick
+  , replicateDist
+  ) where
+
+import Float (i2f, (+.), (*.), (/.))
+import Findall (allValues)
+
+infixl 1 >>>=
+infixr 1 ??
+
+--- Probabilities.
+--- Floating point numbers are used to model probabilities.
+type Probability = Float
+
+--- Probability distributions.
+--- Distributions are abstract and can only be created using the functions
+--- provided by this library, e.g., 'enum' and 'uniform'. Internally, Curry's
+--- built-in non-determinism is used to model distributions with more than one
+--- event-probability pair.
+data Dist a = Dist { event :: a, prob :: Probability }
+
+member :: [a] -> a
+member = foldr (?) failed
+
+--- Creates a distribution based on a given list of events and another list
+--- providing the corresponding probabilities. This function also ensures that
+--- the relevant probabilities add up to `1.0` and are strictly positive.
+enum :: [a] -> [Probability] -> Dist a
+enum xs ps
+  | foldl (+.) 0.0 ps' == 1.0 && all (> 0.0) ps'
+  = member (zipWith Dist xs ps')
+  | otherwise
+  = error ("PFLP.enum: probabilities do not add up to 1.0 " ++
+             "or are not strictly positive")
+ where ps' = take (length xs) ps
+
+--- Creates a uniform distribution based on a given list of events. The list
+--- of events must be non-empty.
+uniform :: [a] -> Dist a
+uniform [] = error "PFLP.uniform: list of events must be non-empty"
+uniform xs@(_:_) = enum xs (repeat (1.0 /. i2f (length xs)))
+
+--- Creates a single-event-distribution with probability `1.0`.
+certainly :: a -> Dist a
+certainly x = Dist x 1.0
+
+--- Combines two (dependent) distributions.
+(>>>=) :: Dist a -> (a -> Dist b) -> Dist b
+d >>>= f = let Dist x p = d
+               Dist y q = f x
+           in Dist y (p *. q)
+
+--- Combines two (independent) distributions with respect to a given function.
+joinWith :: (a -> b -> c) -> Dist a -> Dist b -> Dist c
+joinWith f d1 d2 = d1 >>>= \ x ->
+                   d2 >>>= \ y ->
+                   certainly (f x y)
+
+filterDist :: (a -> Bool) -> Dist a -> Dist a
+filterDist p d | p (event d) = d
+
+--- Queries a distribution for the probabilitiy of events that satisfy a given
+--- predicate.
+(??) :: (a -> Bool) -> Dist a -> Probability
+(??) p = foldr (+.) 0.0 . allValues . prob . filterDist p
+
+--- Run-time choice values. Currently, the only way to construct a run-time
+--- choice value is to explicitly use a lambda abstraction. The evaluation of
+--- a run-time choice can be triggered by the function 'pick'.
+type RT a = () -> a
+
+--- Triggers the evaluation of a run-time choice value (see type synonym 'RT').
+--- Everytime a run-time choice value is evaluated, a new choice is made.
+pick :: RT a -> a
+pick rt = rt ()
+
+--- Independently replicates a distribution a given number of times. In order
+--- to behave properly, the given distribution is required to be a run-time
+--- choice value (see type synonym 'RT').
+replicateDist :: Int -> RT (Dist a) -> Dist [a]
+replicateDist n rt
+  | n == 0    = certainly []
+  | otherwise = joinWith (:) (pick rt) (replicateDist (n - 1) rt)