scheme-clojure-embedded

cond-example.clj

;Scheme
(cond ((> 3 2) 'greater)
      ((< 3 2) 'less)
      (else equal))
;Clojure
(cond (> 3 2) :greater
      (< 3 2) :less)
      :else :equal)

cond.clj

(defmacro cond [& args]
  (when args
    (let [fst# (ffirst args)]
     (list `if (if (= fst# (symbol "else")) :else fst#)
           (second (first args))
           (cons 'cond (next args))))))

cons-example.clj

Scheme
(cons 1 2)
;Clojure
(cons 1 [2])

cons.clj

(defn cons [fst snd]
  (clojure.core/cons fst (if (seq? snd) snd [snd])))

define.clj

(defmacro define [& args]
  `(def ~@args))

display.clj

(def display println)

macroexpand.clj

(macroexpand-1
  '(cond ((< x 0) (- 0 x)) ((= x 0) 100) (else x)))
=> (if (< x 0) (- 0 x) (cond ((= x 0) 100) (else x)))
(clojure.walk/macroexpand-all
  '(cond ((< x 0) (- 0 x)) ((= x 0) 100) (else x)))
=> (if (< x 0) (- 0 x) (if (= x 0) 100 (if :else x nil)))

repl-example

mtscheme v0.1
=> (define (factorial x) (if (= x 0) 1 (* x (factorial (- x 1)))))
#'mtscheme-repl/factorial
=> (factorial 9)
362880.00
=>

repl.clj

(ns mtscheme-repl
  (:refer-clojure :exclude [cond cons let])   ; our DSL re-defines these
  (:use mtscheme))

(defn repl [res]
  (println res)
  (print "=> ")
  (flush)
  (clojure.core/let [l (read-line)]
                    (recur (eval (read-string l)))))

(repl "mtscheme 0.1")

scheme-example.clj

; addition
(+ 1 2)
(+ 1)
; division
(/ 9 3)
(/ 2)
; equality
(= 2 2)
(= 1)
(= 1 (+ 1 1) 1)