Merge pull request #256 from vvakame/impl-ts

[jackhill/mal.git] / mal / step4_if_fn_do.mal

(load-file "../mal/env.mal")
(load-file "../mal/core.mal")

;; read
(def! READ (fn* [strng]
  (read-string strng)))


;; eval
(def! eval-ast (fn* [ast env] (do
  ;;(do (prn "eval-ast" ast "/" (keys env)) )
  (cond
    (symbol? ast) (env-get env ast)

    (list? ast)   (map (fn* [exp] (EVAL exp env)) ast)

    (vector? ast) (apply vector (map (fn* [exp] (EVAL exp env)) ast))

    (map? ast)    (apply hash-map
                      (apply concat
                        (map (fn* [k] [k (EVAL (get ast k) env)])
                             (keys ast))))

    "else"        ast))))

(def! LET (fn* [env args]
  (if (> (count args) 0)
    (do
      (env-set env (nth args 0) (EVAL (nth args 1) env))
      (LET env (rest (rest args)))))))

(def! EVAL (fn* [ast env] (do
  ;;(do (prn "EVAL" ast "/" (keys @env)) )
  (if (not (list? ast))
    (eval-ast ast env)

    ;; apply list
    (let* [a0 (first ast)]
      (cond
        (nil? a0)
        ast

        (= 'def! a0)
        (env-set env (nth ast 1) (EVAL (nth ast 2) env))

        (= 'let* a0)
        (let* [let-env (new-env env)]
          (do
            (LET let-env (nth ast 1))
            (EVAL (nth ast 2) let-env)))

        (= 'do a0)
        (let* [el (eval-ast (rest ast) env)]
          (nth el (- (count el) 1)))

        (= 'if a0)
        (let* [cond (EVAL (nth ast 1) env)]
          (if (or (= cond nil) (= cond false))
            (if (> (count ast) 3)
              (EVAL (nth ast 3) env)
              nil)
            (EVAL (nth ast 2) env)))

        (= 'fn* a0)
        (fn* [& args]
          (EVAL (nth ast 2) (new-env env (nth ast 1) args)))

        "else"
        (let* [el (eval-ast ast env)
              f (first el)
              args (rest el)]
          (apply f args))))))))


;; print
(def! PRINT (fn* [exp] (pr-str exp)))

;; repl
(def! repl-env (new-env))
(def! rep (fn* [strng]
  (PRINT (EVAL (READ strng) repl-env))))

;; core.mal: defined directly using mal
(map (fn* [data] (env-set repl-env (nth data 0) (nth data 1))) core_ns)

;; core.mal: defined using the new language itself 
(rep "(def! not (fn* [a] (if a false true)))")

;; repl loop
(def! repl-loop (fn* []
  (let* [line (readline "mal-user> ")]
    (if line
      (do
        (if (not (= "" line))
          (try*
            (println (rep line))
            (catch* exc
              (println "Uncaught exception:" exc))))
        (repl-loop))))))

(def! -main (fn* [& args] 
  (repl-loop)))
(-main)