#!/usr/bin/env lua local table = require('table') local readline = require('readline') local utils = require('utils') local types = require('types') local reader = require('reader') local printer = require('printer') local Env = require('env') local core = require('core') local List, Vector, HashMap = types.List, types.Vector, types.HashMap -- read function READ(str) return reader.read_str(str) end -- eval function is_pair(x) return types._sequential_Q(x) and #x > 0 end function quasiquote(ast) if not is_pair(ast) then return types.List:new({types.Symbol:new("quote"), ast}) elseif types._symbol_Q(ast[1]) and ast[1].val == 'unquote' then return ast[2] elseif is_pair(ast[1]) and types._symbol_Q(ast[1][1]) and ast[1][1].val == 'splice-unquote' then return types.List:new({types.Symbol:new("concat"), ast[1][2], quasiquote(ast:slice(2))}) else return types.List:new({types.Symbol:new("cons"), quasiquote(ast[1]), quasiquote(ast:slice(2))}) end end function is_macro_call(ast, env) if types._list_Q(ast) and types._symbol_Q(ast[1]) and env:find(ast[1]) then local f = env:get(ast[1]) return types._malfunc_Q(f) and f.ismacro end end function macroexpand(ast, env) while is_macro_call(ast, env) do local mac = env:get(ast[1]) ast = mac.fn(unpack(ast:slice(2))) end return ast end function eval_ast(ast, env) if types._symbol_Q(ast) then return env:get(ast) elseif types._list_Q(ast) then return List:new(utils.map(function(x) return EVAL(x,env) end,ast)) elseif types._vector_Q(ast) then return Vector:new(utils.map(function(x) return EVAL(x,env) end,ast)) elseif types._hash_map_Q(ast) then local new_hm = {} for k,v in pairs(ast) do new_hm[EVAL(k, env)] = EVAL(v, env) end return HashMap:new(new_hm) else return ast end end function EVAL(ast, env) while true do --print("EVAL: "..printer._pr_str(ast,true)) if not types._list_Q(ast) then return eval_ast(ast, env) end -- apply list ast = macroexpand(ast, env) if not types._list_Q(ast) then return eval_ast(ast, env) end local a0,a1,a2,a3 = ast[1], ast[2],ast[3],ast[4] if not a0 then return ast end local a0sym = types._symbol_Q(a0) and a0.val or "" if 'def!' == a0sym then return env:set(a1, EVAL(a2, env)) elseif 'let*' == a0sym then local let_env = Env:new(env) for i = 1,#a1,2 do let_env:set(a1[i], EVAL(a1[i+1], let_env)) end env = let_env ast = a2 -- TCO elseif 'quote' == a0sym then return a1 elseif 'quasiquote' == a0sym then ast = quasiquote(a1) -- TCO elseif 'defmacro!' == a0sym then local mac = EVAL(a2, env) mac.ismacro = true return env:set(a1, mac) elseif 'macroexpand' == a0sym then return macroexpand(a1, env) elseif 'try*' == a0sym then local exc, result = nil, nil xpcall(function() result = EVAL(a1, env) end, function(err) exc = err end) if exc ~= nil then if types._malexception_Q(exc) then exc = exc.val end if a2 and a2[1].val == 'catch*' then result = EVAL(a2[3], Env:new(env, {a2[2]}, {exc})) else types.throw(exc) end end return result elseif 'do' == a0sym then local el = eval_ast(ast:slice(2,#ast-1), env) ast = ast[#ast] -- TCO elseif 'if' == a0sym then local cond = EVAL(a1, env) if cond == types.Nil or cond == false then if a3 then ast = a3 else return types.Nil end -- TCO else ast = a2 -- TCO end elseif 'fn*' == a0sym then return types.MalFunc:new(function(...) return EVAL(a2, Env:new(env, a1, arg)) end, a2, env, a1) else local args = eval_ast(ast, env) local f = table.remove(args, 1) if types._malfunc_Q(f) then ast = f.ast env = Env:new(f.env, f.params, args) -- TCO else return f(unpack(args)) end end end end -- print function PRINT(exp) return printer._pr_str(exp, true) end -- repl local repl_env = Env:new() function rep(str) return PRINT(EVAL(READ(str),repl_env)) end -- core.lua: defined using Lua for k,v in pairs(core.ns) do repl_env:set(types.Symbol:new(k), v) end repl_env:set(types.Symbol:new('eval'), function(ast) return EVAL(ast, repl_env) end) repl_env:set(types.Symbol:new('*ARGV*'), types.List:new(types.slice(arg,2))) -- core.mal: defined using mal rep("(def! *host-language* \"lua\")") rep("(def! not (fn* (a) (if a false true)))") rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))") 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)))))))") rep("(def! *gensym-counter* (atom 0))") rep("(def! gensym (fn* [] (symbol (str \"G__\" (swap! *gensym-counter* (fn* [x] (+ 1 x)))))))") rep("(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) (let* (condvar (gensym)) `(let* (~condvar ~(first xs)) (if ~condvar ~condvar (or ~@(rest xs)))))))))") function print_exception(exc) if exc then if types._malexception_Q(exc) then exc = printer._pr_str(exc.val, true) end print("Error: " .. exc) print(debug.traceback()) end end if #arg > 0 and arg[1] == "--raw" then readline.raw = true table.remove(arg,1) end if #arg > 0 then xpcall(function() rep("(load-file \""..arg[1].."\")") end, print_exception) os.exit(0) end rep("(println (str \"Mal [\" *host-language* \"]\"))") while true do line = readline.readline("user> ") if not line then break end xpcall(function() print(rep(line)) end, print_exception) end