simplifier-clojure

core_match.clj

(ns clj-automated-reasoning.core-match
  (:require [clojure.core.match :as cm]))

(defn simplify1 [e]
  (cm/match [e]
    [(['+ 0 x] :seq)] x
    [(['+ x 0] :seq)] x
    [(['* x 1] :seq)] x
    [(['* 1 x] :seq)] x
    [(['* x 0] :seq)] 0
    [(['* 0 x] :seq)] 0
    [(['+ (x :guard number?) (y :guard number?)] :seq)] (+ x y)
    [(['* (x :guard number?) (y :guard number?)] :seq)] (* x y)
    :else e))

(defn simplify [e]
  (simplify1
   (cm/match [e]
     [(['+ x y] :seq)] (list '+ (simplify x) (simplify y))
     [(['* x y] :seq)] (list '* (simplify x) (simplify y))
     :else e)))

(println (simplify '(+ (* (+ 1 (* 0 x)) 3) 12)))

plain.clj

(ns clj-automated-reasoning.plain)

(defn simplify1 [e]
  (if-not (sequential? e)
    e
    (let [[operator & [op1 op2]] e]
      (case operator
        + (cond
            (= 0 op1) op2
            (= 0 op2) op1
            (and (number? op1) (number? op2)) (+ op1 op2)
            :else e)
        * (cond
            (= 0 op1) 0
            (= 0 op2) 0
            (= 1 op1) op2
            (= 1 op2) op1
            (and (number? op1) (number? op2)) (+ op1 op2)
            :else e)
        e))))

(defn simplify [e]
  (simplify1
   (if-not (sequential? e)
     e
     (let [[operator & [op1 op2]] e]
       (case operator
         + (list '+ (simplify op1) (simplify op2))
         * (list '* (simplify op1) (simplify op2))
         e)))))

(println (simplify '(+ (* (+ 1 (* 0 x)) 3) 12)))