dart/step1_read_print.dart

   1 import 'dart:io';
   2
   3 import 'printer.dart' as printer;
   4 import 'reader.dart' as reader;
   5 import 'types.dart';
   6
   7 MalType READ(String x) => reader.read_str(x);
   8
   9 MalType EVAL(MalType x) => x;
  10
  11 String PRINT(MalType x) => printer.pr_str(x);
  12
  13 String rep(String x) {
  14   return PRINT(EVAL(READ(x)));
  15 }
  16
  17 const prompt = 'user> ';
  18 main() {
  19   while (true) {
  20     stdout.write(prompt);
  21     var input = stdin.readLineSync();
  22     if (input == null) return;
  23     var output;
  24     try {
  25       output = rep(input);
  26     } on reader.ParseException catch (e) {
  27       stdout.writeln("Error: '${e.message}'");
  28       continue;
  29     } on reader.NoInputException {
  30       continue;
  31     }
  32     stdout.writeln(output);
  33   }
  34 }