rpython/step8_macros.py

   1 import sys, traceback
   2 import mal_readline
   3 import mal_types as types
   4 from mal_types import (MalSym, MalInt, MalStr,
   5                        nil, true, false, _symbol, _keywordu,
   6                        MalList, _list, MalVector, MalHashMap, MalFunc)
   7 import reader, printer
   8 from env import Env
   9 import core
  10
  11 # read
  12 def READ(str):
  13     return reader.read_str(str)
  14
  15 # eval
  16 def is_pair(x):
  17     return types._sequential_Q(x) and len(x) > 0
  18
  19 def quasiquote(ast):
  20     if not is_pair(ast):
  21         return _list(_symbol(u"quote"), ast)
  22     else:
  23         a0 = ast[0]
  24         if isinstance(a0, MalSym):
  25             if a0.value == u'unquote':
  26                 return ast[1]
  27         if is_pair(a0) and isinstance(a0[0], MalSym):
  28             a00 = a0[0]
  29             if (isinstance(a00, MalSym) and
  30                 a00.value == u'splice-unquote'):
  31                 return _list(_symbol(u"concat"),
  32                              a0[1],
  33                              quasiquote(ast.rest()))
  34     return _list(_symbol(u"cons"),
  35                 quasiquote(a0),
  36                 quasiquote(ast.rest()))
  37
  38 def is_macro_call(ast, env):
  39     if types._list_Q(ast):
  40         a0 = ast[0]
  41         if isinstance(a0, MalSym):
  42             if not env.find(a0) is None:
  43                 return env.get(a0).ismacro
  44     return False
  45
  46 def macroexpand(ast, env):
  47     while is_macro_call(ast, env):
  48         assert isinstance(ast[0], MalSym)
  49         mac = env.get(ast[0])
  50         ast = macroexpand(mac.apply(ast.rest()), env)
  51     return ast
  52
  53 def eval_ast(ast, env):
  54     if types._symbol_Q(ast):
  55         assert isinstance(ast, MalSym)
  56         return env.get(ast)
  57     elif types._list_Q(ast):
  58         res = []
  59         for a in ast.values:
  60             res.append(EVAL(a, env))
  61         return MalList(res)
  62     elif types._vector_Q(ast):
  63         res = []
  64         for a in ast.values:
  65             res.append(EVAL(a, env))
  66         return MalVector(res)
  67     elif types._hash_map_Q(ast):
  68         new_dct = {}
  69         for k in ast.dct.keys():
  70             new_dct[k] = EVAL(ast.dct[k], env)
  71         return MalHashMap(new_dct)
  72     else:
  73         return ast  # primitive value, return unchanged
  74
  75 def EVAL(ast, env):
  76     while True:
  77         #print("EVAL %s" % printer._pr_str(ast))
  78         if not types._list_Q(ast):
  79             return eval_ast(ast, env)
  80
  81         # apply list
  82         ast = macroexpand(ast, env)
  83         if not types._list_Q(ast): return ast
  84         if len(ast) == 0: return ast
  85         a0 = ast[0]
  86         if isinstance(a0, MalSym):
  87             a0sym = a0.value
  88         else:
  89             a0sym = u"__<*fn*>__"
  90
  91         if u"def!" == a0sym:
  92             a1, a2 = ast[1], ast[2]
  93             res = EVAL(a2, env)
  94             return env.set(a1, res)
  95         elif u"let*" == a0sym:
  96             a1, a2 = ast[1], ast[2]
  97             let_env = Env(env)
  98             for i in range(0, len(a1), 2):
  99                 let_env.set(a1[i], EVAL(a1[i+1], let_env))
 100             ast = a2
 101             env = let_env # Continue loop (TCO)
 102         elif u"quote" == a0sym:
 103             return ast[1]
 104         elif u"quasiquote" == a0sym:
 105             ast = quasiquote(ast[1]) # Continue loop (TCO)
 106         elif u"defmacro!" == a0sym:
 107             func = EVAL(ast[2], env)
 108             func.ismacro = True
 109             return env.set(ast[1], func)
 110         elif u"macroexpand" == a0sym:
 111             return macroexpand(ast[1], env)
 112         elif u"do" == a0sym:
 113             if len(ast) == 0:
 114                 return nil
 115             elif len(ast) > 1:
 116                 eval_ast(ast.slice2(1, len(ast)-1), env)
 117             ast = ast[-1] # Continue loop (TCO)
 118         elif u"if" == a0sym:
 119             a1, a2 = ast[1], ast[2]
 120             cond = EVAL(a1, env)
 121             if cond is nil or cond is false:
 122                 if len(ast) > 3: ast = ast[3] # Continue loop (TCO)
 123                 else:            return nil
 124             else:
 125                 ast = a2 # Continue loop (TCO)
 126         elif u"fn*" == a0sym:
 127             a1, a2 = ast[1], ast[2]
 128             return MalFunc(None, a2, env, a1, EVAL)
 129         else:
 130             el = eval_ast(ast, env)
 131             f = el.values[0]
 132             if isinstance(f, MalFunc):
 133                 if f.ast:
 134                     ast = f.ast
 135                     env = f.gen_env(el.rest()) # Continue loop (TCO)
 136                 else:
 137                     return f.apply(el.rest())
 138             else:
 139                 raise Exception("%s is not callable" % f)
 140
 141 # print
 142 def PRINT(exp):
 143     return printer._pr_str(exp)
 144
 145 # repl
 146 class MalEval(MalFunc):
 147     def apply(self, args):
 148         return self.EvalFunc(args[0], self.env)
 149
 150 def entry_point(argv):
 151     repl_env = Env()
 152     def REP(str, env):
 153         return PRINT(EVAL(READ(str), env))
 154
 155     # core.py: defined using python
 156     for k, v in core.ns.items():
 157         repl_env.set(_symbol(unicode(k)), MalFunc(v))
 158     repl_env.set(types._symbol(u'eval'),
 159                  MalEval(None, env=repl_env, EvalFunc=EVAL))
 160     mal_args = []
 161     if len(argv) >= 3:
 162         for a in argv[2:]: mal_args.append(MalStr(unicode(a)))
 163     repl_env.set(_symbol(u'*ARGV*'), MalList(mal_args))
 164
 165     # core.mal: defined using the language itself
 166     REP("(def! not (fn* (a) (if a false true)))", repl_env)
 167     REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))", repl_env)
 168     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)))))))", repl_env)
 169     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))))))))", repl_env)
 170
 171     if len(argv) >= 2:
 172         REP('(load-file "' + argv[1] + '")', repl_env)
 173         return 0
 174
 175     while True:
 176         try:
 177             line = mal_readline.readline("user> ")
 178             if line == "": continue
 179             print(REP(line, repl_env))
 180         except EOFError as e:
 181             break
 182         except reader.Blank:
 183             continue
 184         except types.MalException as e:
 185             print(u"Error: %s" % printer._pr_str(e.object, False))
 186         except Exception as e:
 187             print("Error: %s" % e)
 188             #print("".join(traceback.format_exception(*sys.exc_info())))
 189     return 0
 190
 191 # _____ Define and setup target ___
 192 def target(*args):
 193     return entry_point
 194
 195 # Just run entry_point if not RPython compilation
 196 import sys
 197 if not sys.argv[0].endswith('rpython'):
 198     entry_point(sys.argv)