(ns emptyhead.newlib.math.arithmetic
  "Airthmetic operators."
  (:require [emptyhead.thought.define :as def]
            [emptyhead.thought.crud :as thought]
            [emptyhead.newlib.message :as msg]))

;; Initial addition, e.g. =5 +=. Returns partially applied pointer.
(def/define! [:EH :PRIM [:EH :PRIM :NUM] :+]
  (fn [thought parent]
    (let [to (:to (thought/data parent))
          pointer (-> (str "PART<" to "+_>.") gensym keyword)
          th (thought/register-thought! [:EH :PRIM :PARTIAL :+] :transient false :data to)]
      (msg/register-impl pointer [:EH :PRIM :NUM] th)
      [parent pointer])))

;; Final addition, e.g. =(5 +) 5=. Returns a thunk.
(def/define! [:EH :PRIM :PARTIAL :+]
  (fn [thought parent]
    (let [from (:from (thought/data parent))
          to (thought/data thought)
          pointer (-> (str "LAZY<" from "+" to">.") gensym keyword)
          lazy (thought/register-thought! [:EH :PRIM :LAZY :+] :transient true :data [from to])]
      (msg/register-impl pointer [:EH :PRIM :REIFY] lazy)
      [parent pointer])))

(def/define! [:EH :PRIM :LAZY :+]
  (fn [thought parent]
    (let [[from to] (thought/data thought)]
      [parent (+ from to)])))