picolisp/step2_eval.l

   1 (de load-relative (Path)
   2    (load (pack (car (file)) Path)) )
   3
   4 (load-relative "readline.l")
   5 (load-relative "types.l")
   6 (load-relative "reader.l")
   7 (load-relative "printer.l")
   8
   9 (de READ (String)
  10    (read-str String) )
  11
  12 (def '*ReplEnv
  13    '((+ . ((A B) (MAL-number (+ (MAL-value A) (MAL-value B)))))
  14      (- . ((A B) (MAL-number (- (MAL-value A) (MAL-value B)))))
  15      (* . ((A B) (MAL-number (* (MAL-value A) (MAL-value B)))))
  16      (/ . ((A B) (MAL-number (/ (MAL-value A) (MAL-value B))))) ) )
  17
  18 (de EVAL (Ast Env)
  19    (if (= (MAL-type Ast) 'list)
  20       (if (not (MAL-value Ast))
  21          Ast
  22          (let Value (MAL-value (eval-ast Ast Env))
  23             (apply (car Value) (cdr Value)) ) )
  24       (eval-ast Ast Env) ) )
  25
  26 (de eval-ast (Ast Env)
  27    (let Value (MAL-value Ast)
  28       (case (MAL-type Ast)
  29          (symbol
  30             (if (assoc Value Env)
  31                (cdr @)
  32                (throw 'err (MAL-error (MAL-string (pack "'" Value "' not found")))) ) )
  33          (list (MAL-list (mapcar '((Form) (EVAL Form Env)) Value)))
  34          (vector (MAL-vector (mapcar '((Form) (EVAL Form Env)) Value)))
  35          (map (MAL-map (mapcar '((Form) (EVAL Form Env)) Value)))
  36          (T Ast) ) ) )
  37
  38 (de PRINT (Ast)
  39    (pr-str Ast T) )
  40
  41 (de rep (String)
  42    (PRINT (EVAL (READ String) *ReplEnv)) )
  43
  44 (load-history ".mal_history")
  45
  46 (use Eof
  47    (until Eof
  48       (let Input (readline "user> ")
  49          (if (=0 Input)
  50             (setq Eof T)
  51             (let Output (catch 'err (rep Input))
  52                 (if (isa '+MALError Output)
  53                    (let Message (MAL-value Output)
  54                       (unless (= (MAL-value Message) "end of token stream")
  55                          (prinl "[error] " (pr-str Message)) ) )
  56                    (prinl Output) ) ) ) ) ) )
  57
  58 (prinl)
  59 (bye)