lua/step1_read_print.lua

   1 #!/usr/bin/env lua
   2
   3 local readline = require('readline')
   4 local utils = require('utils')
   5 local reader = require('reader')
   6 local printer = require('printer')
   7
   8 -- read
   9 function READ(str)
  10     return reader.read_str(str)
  11 end
  12
  13 -- eval
  14 function EVAL(ast, env)
  15     return ast
  16 end
  17
  18 -- print
  19 function PRINT(exp)
  20     return printer._pr_str(exp, true)
  21 end
  22
  23 -- repl
  24 function rep(str)
  25     return PRINT(EVAL(READ(str),""))
  26 end
  27
  28 while true do
  29     line = readline.readline("user> ")
  30     if not line then break end
  31     xpcall(function()
  32         print(rep(line))
  33     end, function(exc)
  34         if exc then
  35             if types._malexception_Q(exc) then
  36                 exc = printer._pr_str(exc.val, true)
  37             end
  38             print("Error: " .. exc)
  39             print(debug.traceback())
  40         end
  41     end)
  42 end