es6/step1_read_print.mjs

   1 import rl from './node_readline.js'
   2 const readline = rl.readline
   3 import { BlankException, read_str } from './reader'
   4 import { pr_str } from './printer'
   5
   6 // read
   7 const READ = str => read_str(str)
   8
   9 // eval
  10 const EVAL = (ast, env) => ast
  11
  12 // print
  13 const PRINT = exp => pr_str(exp, true)
  14
  15 // repl
  16 const REP = str => PRINT(EVAL(READ(str), {}))
  17
  18 while (true) {
  19     let line = readline('user> ')
  20     if (line == null) break
  21     try {
  22         if (line) { console.log(REP(line)) }
  23     } catch (exc) {
  24         if (exc instanceof BlankException) { continue }
  25         if (exc instanceof Error) { console.warn(exc.stack) }
  26         else { console.warn(`Error: ${exc}`) }
  27     }
  28 }