coffee/step6_file.coffee

   1 readline = require "./node_readline.coffee"
   2 types = require "./types.coffee"
   3 reader = require "./reader.coffee"
   4 printer = require "./printer.coffee"
   5 Env = require("./env.coffee").Env
   6 core = require("./core.coffee")
   7
   8 # read
   9 READ = (str) -> reader.read_str str
  10
  11 # eval
  12 eval_ast = (ast, env) ->
  13   if types._symbol_Q(ast) then env.get ast
  14   else if types._list_Q(ast) then ast.map((a) -> EVAL(a, env))
  15   else if types._vector_Q(ast)
  16     types._vector(ast.map((a) -> EVAL(a, env))...)
  17   else if types._hash_map_Q(ast)
  18     new_hm = {}
  19     new_hm[k] = EVAL(ast[k],env) for k,v of ast
  20     new_hm
  21   else ast
  22
  23 EVAL = (ast, env) ->
  24  loop
  25   #console.log "EVAL:", printer._pr_str ast
  26   if !types._list_Q ast then return eval_ast ast, env
  27   if ast.length == 0 then return ast
  28
  29   # apply list
  30   [a0, a1, a2, a3] = ast
  31   switch a0.name
  32     when "def!"
  33       return env.set(a1, EVAL(a2, env))
  34     when "let*"
  35       let_env = new Env(env)
  36       for k,i in a1 when i %% 2 == 0
  37         let_env.set(a1[i], EVAL(a1[i+1], let_env))
  38       ast = a2
  39       env = let_env
  40     when "do"
  41       eval_ast(ast[1..-2], env)
  42       ast = ast[ast.length-1]
  43     when "if"
  44       cond = EVAL(a1, env)
  45       if cond == null or cond == false
  46         if a3? then ast = a3 else return null
  47       else
  48         ast = a2
  49     when "fn*"
  50       return types._function(EVAL, a2, env, a1)
  51     else
  52       [f, args...] = eval_ast ast, env
  53       if types._function_Q(f)
  54         ast = f.__ast__
  55         env = f.__gen_env__(args)
  56       else
  57         return f(args...)
  58
  59
  60 # print
  61 PRINT = (exp) -> printer._pr_str exp, true
  62
  63 # repl
  64 repl_env = new Env()
  65 rep = (str) -> PRINT(EVAL(READ(str), repl_env))
  66
  67 # core.coffee: defined using CoffeeScript
  68 repl_env.set types._symbol(k), v for k,v of core.ns
  69 repl_env.set types._symbol('eval'), (ast) -> EVAL(ast, repl_env)
  70 repl_env.set types._symbol('*ARGV*'), []
  71
  72 # core.mal: defined using the language itself
  73 rep("(def! not (fn* (a) (if a false true)))");
  74 rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \"\nnil)\")))))");
  75
  76 if process? && process.argv.length > 2
  77   repl_env.set types._symbol('*ARGV*'), process.argv[3..]
  78   rep('(load-file "' + process.argv[2] + '")')
  79   process.exit 0
  80
  81 # repl loop
  82 while (line = readline.readline("user> ")) != null
  83   continue if line == ""
  84   try
  85     console.log rep line
  86   catch exc
  87     continue if exc instanceof reader.BlankException
  88     if exc.stack? and exc.stack.length > 2000
  89       console.log exc.stack.slice(0,1000) + "\n  ..." + exc.stack.slice(-1000)
  90     else if exc.stack? then console.log exc.stack
  91     else                    console.log exc
  92
  93 # vim: ts=2:sw=2