skew/step1_read_print.sk

   1 def READ(str string) MalVal {
   2   return read_str(str)
   3 }
   4
   5 def EVAL(ast MalVal, env StringMap<string>) MalVal {
   6   return ast
   7 }
   8
   9 def PRINT(exp MalVal) string {
  10   return exp?.print(true)
  11 }
  12
  13 def REP(str string) string {
  14   return PRINT(EVAL(READ(str), {}))
  15 }
  16
  17 @entry
  18 def main {
  19   var line string
  20   while (line = readLine("user> ")) != null {
  21     if line == "" { continue }
  22     try {
  23       printLn(REP(line))
  24     }
  25     catch e MalError {
  26       printLn("Error: \(e.message)")
  27     }
  28   }
  29 }