julia/step9_try.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 ismacroCall(ast, env)
  34     return isa(ast, Array) &&
  35            isa(ast[1], Symbol) &&
  36            env_find(env, ast[1]) != nothing &&
  37            isa(env_get(env, ast[1]), MalFunc) &&
  38            env_get(env, ast[1]).ismacro
  39 end
  40
  41 function macroexpand(ast, env)
  42     while ismacroCall(ast, env)
  43         mac = env_get(env, ast[1])
  44         ast = mac.fn(ast[2:end]...)
  45     end
  46     ast
  47 end
  48
  49 function eval_ast(ast, env)
  50     if typeof(ast) == Symbol
  51         env_get(env,ast)
  52     elseif isa(ast, Array) || isa(ast, Tuple)
  53         map((x) -> EVAL(x,env), ast)
  54     elseif isa(ast, Dict)
  55         [EVAL(x[1],env) => EVAL(x[2], env) for x=ast]
  56     else
  57         ast
  58     end
  59 end
  60
  61 function EVAL(ast, env)
  62   while true
  63     #println("EVAL: $(printer.pr_str(ast,true))")
  64     if !isa(ast, Array) return eval_ast(ast, env) end
  65
  66     # apply
  67     ast = macroexpand(ast, env)
  68     if !isa(ast, Array) return ast end
  69
  70     if     :def! == ast[1]
  71         return env_set(env, ast[2], EVAL(ast[3], env))
  72     elseif symbol("let*") == ast[1]
  73         let_env = Env(env)
  74         for i = 1:2:length(ast[2])
  75             env_set(let_env, ast[2][i], EVAL(ast[2][i+1], let_env))
  76         end
  77         env = let_env
  78         ast = ast[3]
  79         # TCO loop
  80     elseif :quote == ast[1]
  81         return ast[2]
  82     elseif :quasiquote == ast[1]
  83         ast = quasiquote(ast[2])
  84         # TCO loop
  85     elseif :defmacro! == ast[1]
  86         func = EVAL(ast[3], env)
  87         func.ismacro = true
  88         return env_set(env, ast[2], func)
  89     elseif :macroexpand == ast[1]
  90         return macroexpand(ast[2], env)
  91     elseif symbol("try*") == ast[1]
  92         try
  93             return EVAL(ast[2], env)
  94         catch exc
  95             e = string(exc)
  96             if isa(exc, MalException)
  97                 e = exc.malval
  98             elseif isa(exc, ErrorException)
  99                 e = exc.msg
 100             else
 101                 e = string(e)
 102             end
 103             if length(ast) > 2 && ast[3][1] == symbol("catch*")
 104                 return EVAL(ast[3][3], Env(env, Any[ast[3][2]], Any[e]))
 105             else
 106                 rethrow(exc)
 107             end
 108         end
 109     elseif :do == ast[1]
 110         eval_ast(ast[2:end-1], env)
 111         ast = ast[end]
 112         # TCO loop
 113     elseif :if == ast[1]
 114         cond = EVAL(ast[2], env)
 115         if cond === nothing || cond === false
 116             if length(ast) >= 4
 117                 ast = ast[4]
 118                 # TCO loop
 119             else
 120                 return nothing
 121             end
 122         else
 123             ast = ast[3]
 124             # TCO loop
 125         end
 126     elseif symbol("fn*") == ast[1]
 127         return MalFunc(
 128             (args...) -> EVAL(ast[3], Env(env, ast[2], args)),
 129             ast[3], env, ast[2])
 130     else
 131         el = eval_ast(ast, env)
 132         f, args = el[1], el[2:end]
 133         if isa(f, MalFunc)
 134             ast = f.ast
 135             env = Env(f.env, f.params, args)
 136             # TCO loop
 137         else
 138             return f(args...)
 139         end
 140     end
 141   end
 142 end
 143
 144 # PRINT
 145 function PRINT(exp)
 146     printer.pr_str(exp)
 147 end
 148
 149 # REPL
 150 repl_env = nothing
 151 function REP(str)
 152     return PRINT(EVAL(READ(str), repl_env))
 153 end
 154
 155 # core.jl: defined using Julia
 156 repl_env = Env(nothing, core.ns)
 157 env_set(repl_env, :eval, (ast) -> EVAL(ast, repl_env))
 158 env_set(repl_env, symbol("*ARGV*"), ARGS[2:end])
 159
 160 # core.mal: defined using the language itself
 161 REP("(def! not (fn* (a) (if a false true)))")
 162 REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))")
 163 REP("(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))")
 164 REP("(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))")
 165
 166
 167 if length(ARGS) > 0
 168     REP("(load-file \"$(ARGS[1])\")")
 169     exit(0)
 170 end
 171
 172 while true
 173     line = readline_mod.do_readline("user> ")
 174     if line === nothing break end
 175     try
 176         println(REP(line))
 177     catch e
 178         if isa(e, ErrorException)
 179             println("Error: $(e.msg)")
 180         else
 181             println("Error: $(string(e))")
 182         end
 183         # TODO: show at least part of stack
 184         if !isa(e, StackOverflowError)
 185             bt = catch_backtrace()
 186             Base.show_backtrace(STDERR, bt)
 187         end
 188         println()
 189     end
 190 end