coffee: Fix exception on literal empty list
[jackhill/mal.git] / coffee / step5_tco.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
70 # core.mal: defined using the language itself
71 rep("(def! not (fn* (a) (if a false true)))");
72
73 # repl loop
74 while (line = readline.readline("user> ")) != null
75 continue if line == ""
76 try
77 console.log rep line
78 catch exc
79 continue if exc instanceof reader.BlankException
80 if exc.stack? and exc.stack.length > 2000
81 console.log exc.stack.slice(0,1000) + "\n ..." + exc.stack.slice(-1000)
82 else if exc.stack? console.log exc.stack
83 else console.log exc
84
85 # vim: ts=2:sw=2