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 if #arg > 0 and arg[1] == "--raw" then
  29     readline.raw = true
  30 end
  31
  32 while true do
  33     line = readline.readline("user> ")
  34     if not line then break end
  35     xpcall(function()
  36         print(rep(line))
  37     end, function(exc)
  38         if exc then
  39             if types._malexception_Q(exc) then
  40                 exc = printer._pr_str(exc.val, true)
  41             end
  42             print("Error: " .. exc)
  43             print(debug.traceback())
  44         end
  45     end)
  46 end