scheme/step0_repl.scm

   1 (import (scheme base))
   2 (import (scheme write))
   3
   4 (define (READ input)
   5   input)
   6
   7 (define (EVAL input)
   8   input)
   9
  10 (define (PRINT input)
  11   input)
  12
  13 (define (rep input)
  14   (PRINT (EVAL (READ input))))
  15
  16 (define (readline prompt)
  17   (display prompt)
  18   (flush-output-port)
  19   (let ((input (read-line)))
  20     (if (eof-object? input)
  21         #f
  22         input)))
  23
  24 (define (main)
  25   (let loop ()
  26     (let ((input (readline "user> ")))
  27       (when input
  28         (display (rep input))
  29         (newline)
  30         (loop))))
  31   (newline))
  32
  33 (main)