Klipse Anglican experiment.

anglican_experiment.clj

(ns anglican.runtime$macros
  "Runtime library"
  (:require [clojure.string :as str]
            [clojure.core.matrix :as m]
            [clojure.core.matrix.linear :as ml]
            [anglican.runtime :refer [distribution]]

            #?(:cljs [goog.string.format]))
  )

(defn- cljs-env?
  "Take the &env from a macro, and tell whether we are expanding into cljs."
  [env]
  (boolean (:ns env)))


   (defmacro if-cljs
     "Return then if we are generating cljs code and else for Clojure code.
     https://groups.google.com/d/msg/clojurescript/iBY5HaQda4A/w1lAQi9_AwsJ"
     [then else]
     (if (cljs-env? &env) then else))



(defn format
    "Similar to Java String's format function for cljs."
    [s & args]
    (goog.string.format s (into-array args)))

(defprotocol distribution
  "random distribution"
  (sample* [this]
    "draws a sample from the distribution")
  (observe* [this value]
    "return the probability [density] of the value"))

(defmacro defdist
  "defines distribution"
  [name & args]
  (let [[docstring parameters & args]
        (if (string? (first args))
          args
          `(~(format "%s distribution" name) ~@args))
        [bindings & methods]
        (if (vector? (first args))
          args
          `[[] ~@args])
        record-name (symbol (format "%s-distribution" name))
        variables (take-nth 2 bindings)]
    `(do
       (declare ~name)
       (defrecord ~record-name [~@parameters ~@variables]
         ;; TODO
;         Object
;         (toString [~'this]
;           (str (list '~(qualify name) ~@parameters)))
         anglican.runtime$macros$distribution
         ~@methods)
       (defn ~name ~docstring ~parameters
         (let ~bindings
           (~(symbol (format "->%s" record-name))
                     ~@parameters ~@variables)))
       (if-cljs
        (extend-protocol cljs.core/IPrintWithWriter
          ~record-name
          (cljs.core/-pr-writer [o# writer# opts#]
            (cljs.core/-write writer# (str o#))))
        ;; TODO macro hygene?
        (defmethod print-method ~record-name
          [~'o ~'m]
          (print-simple (str ~'o) ~'m))))))

(do
  ;; bootstrap the uniform distribution
  ;; was imported from Apache Commons
  (defrecord uniform-continuous-distribution [min max]
    anglican.runtime$macros/distribution
    (sample* [this]
      (let [len (- max min)]
        (+ min (* len (rand)))))
    (observe* [this value]
      (if (<= min value  max)
        (log (/ 1 (- max min)))
        js/Number.NEGATIVE_INFINITY)))

  (defn uniform-continuous
    "Uniform continuous distribution"
    [min max]
    (->uniform-continuous-distribution min max))


  (extend-protocol cljs.core/IPrintWithWriter
    uniform-continuous-distribution
    (cljs.core/-pr-writer
      [o writer opts]
      (cljs.core/-write writer (str (type o))))))


(sample* (uniform-continuous 0 3))


(anglican.runtime$macros/defdist bernoulli
  "Bernoulli distribution"
  [p] [dist (uniform-continuous 0.0 1.0)]
  (sample* [this] (if (< (sample* dist) p) 1 0))
  (observe* [this value]
    (log (case value
           1 p
           0 (- 1. p)
           0.))))

(sample* (bernoulli 0.8))