julia/step7_quote.jl

   1 #!/usr/bin/env julia
   2
   3 push!(LOAD_PATH, pwd(), "/usr/share/julia/base")
   4 import readline_mod
   5 import reader
   6 import printer
   7 using env
   8 import core
   9 using types
  10
  11 # READ
  12 function READ(str)
  13     reader.read_str(str)
  14 end
  15
  16 # EVAL
  17 function ispair(ast)
  18     (isa(ast, Array) || isa(ast, Tuple)) && length(ast) > 0
  19 end
  20
  21 function quasiquote(ast)
  22     if !ispair(ast)
  23         [[:quote]; Any[ast]]
  24     elseif ast[1] == :unquote
  25         ast[2]
  26     elseif ispair(ast[1]) && ast[1][1] == symbol("splice-unquote")
  27         [[:concat]; Any[ast[1][2]]; Any[quasiquote(ast[2:end])]]
  28     else
  29         [[:cons]; Any[quasiquote(ast[1])]; Any[quasiquote(ast[2:end])]]
  30     end
  31 end
  32
  33 function eval_ast(ast, env)
  34     if typeof(ast) == Symbol
  35         env_get(env,ast)
  36     elseif isa(ast, Array) || isa(ast, Tuple)
  37         map((x) -> EVAL(x,env), ast)
  38     elseif isa(ast, Dict)
  39         [EVAL(x[1],env) => EVAL(x[2], env) for x=ast]
  40     else
  41         ast
  42     end
  43 end
  44
  45 function EVAL(ast, env)
  46   while true
  47     #println("EVAL: $(printer.pr_str(ast,true))")
  48     if !isa(ast, Array) return eval_ast(ast, env) end
  49     if isempty(ast) return ast end
  50
  51     # apply
  52     if     :def! == ast[1]
  53         return env_set(env, ast[2], EVAL(ast[3], env))
  54     elseif symbol("let*") == ast[1]
  55         let_env = Env(env)
  56         for i = 1:2:length(ast[2])
  57             env_set(let_env, ast[2][i], EVAL(ast[2][i+1], let_env))
  58         end
  59         env = let_env
  60         ast = ast[3]
  61         # TCO loop
  62     elseif :quote == ast[1]
  63         return ast[2]
  64     elseif :quasiquote == ast[1]
  65         ast = quasiquote(ast[2])
  66         # TCO loop
  67     elseif :do == ast[1]
  68         eval_ast(ast[2:end-1], env)
  69         ast = ast[end]
  70         # TCO loop
  71     elseif :if == ast[1]
  72         cond = EVAL(ast[2], env)
  73         if cond === nothing || cond === false
  74             if length(ast) >= 4
  75                 ast = ast[4]
  76                 # TCO loop
  77             else
  78                 return nothing
  79             end
  80         else
  81             ast = ast[3]
  82             # TCO loop
  83         end
  84     elseif symbol("fn*") == ast[1]
  85         return MalFunc(
  86             (args...) -> EVAL(ast[3], Env(env, ast[2], Any[args...])),
  87             ast[3], env, ast[2])
  88     else
  89         el = eval_ast(ast, env)
  90         f, args = el[1], el[2:end]
  91         if isa(f, MalFunc)
  92             ast = f.ast
  93             env = Env(f.env, f.params, args)
  94             # TCO loop
  95         else
  96             return f(args...)
  97         end
  98     end
  99   end
 100 end
 101
 102 # PRINT
 103 function PRINT(exp)
 104     printer.pr_str(exp)
 105 end
 106
 107 # REPL
 108 repl_env = nothing
 109 function REP(str)
 110     return PRINT(EVAL(READ(str), repl_env))
 111 end
 112
 113 # core.jl: defined using Julia
 114 repl_env = Env(nothing, core.ns)
 115 env_set(repl_env, :eval, (ast) -> EVAL(ast, repl_env))
 116 env_set(repl_env, symbol("*ARGV*"), ARGS[2:end])
 117
 118 # core.mal: defined using the language itself
 119 REP("(def! not (fn* (a) (if a false true)))")
 120 REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))")
 121
 122 if length(ARGS) > 0
 123     REP("(load-file \"$(ARGS[1])\")")
 124     exit(0)
 125 end
 126
 127 while true
 128     line = readline_mod.do_readline("user> ")
 129     if line === nothing break end
 130     try
 131         println(REP(line))
 132     catch e
 133         if isa(e, ErrorException)
 134             println("Error: $(e.msg)")
 135         else
 136             println("Error: $(string(e))")
 137         end
 138         # TODO: show at least part of stack
 139         if !isa(e, StackOverflowError)
 140             bt = catch_backtrace()
 141             Base.show_backtrace(STDERR, bt)
 142         end
 143         println()
 144     end
 145 end