impls/rpython/step7_quote.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 qq_loop(elt, acc):
  17     if types._list_Q(elt) and len(elt) == 2:
  18         fst = elt[0]
  19         if isinstance(fst, MalSym) and fst.value == u"splice-unquote":
  20             return _list(_symbol(u"concat"), elt[1], acc)
  21     return _list(_symbol(u"cons"), quasiquote(elt), acc)
  22
  23 def qq_foldr(seq):
  24     acc = _list()
  25     for elt in reversed(seq):
  26         acc = qq_loop (elt, acc)
  27     return acc
  28
  29 def quasiquote(ast):
  30     if types._list_Q(ast):
  31         if len(ast) == 2:
  32             fst = ast[0]
  33             if isinstance(fst, MalSym) and fst.value == u"unquote":
  34                 return ast[1]
  35         return qq_foldr(ast.values)
  36     elif types._vector_Q(ast):
  37         return _list(_symbol(u"vec"), qq_foldr(ast.values))
  38     elif types._symbol_Q(ast) or types._hash_map_Q(ast):
  39         return _list(_symbol(u"quote"), ast)
  40     else:
  41         return ast
  42
  43 def eval_ast(ast, env):
  44     if types._symbol_Q(ast):
  45         assert isinstance(ast, MalSym)
  46         return env.get(ast)
  47     elif types._list_Q(ast):
  48         res = []
  49         for a in ast.values:
  50             res.append(EVAL(a, env))
  51         return MalList(res)
  52     elif types._vector_Q(ast):
  53         res = []
  54         for a in ast.values:
  55             res.append(EVAL(a, env))
  56         return MalVector(res)
  57     elif types._hash_map_Q(ast):
  58         new_dct = {}
  59         for k in ast.dct.keys():
  60             new_dct[k] = EVAL(ast.dct[k], env)
  61         return MalHashMap(new_dct)
  62     else:
  63         return ast  # primitive value, return unchanged
  64
  65 def EVAL(ast, env):
  66     while True:
  67         #print("EVAL %s" % printer._pr_str(ast))
  68         if not types._list_Q(ast):
  69             return eval_ast(ast, env)
  70
  71         # apply list
  72         if len(ast) == 0: return ast
  73         a0 = ast[0]
  74         if isinstance(a0, MalSym):
  75             a0sym = a0.value
  76         else:
  77             a0sym = u"__<*fn*>__"
  78
  79         if u"def!" == a0sym:
  80             a1, a2 = ast[1], ast[2]
  81             res = EVAL(a2, env)
  82             return env.set(a1, res)
  83         elif u"let*" == a0sym:
  84             a1, a2 = ast[1], ast[2]
  85             let_env = Env(env)
  86             for i in range(0, len(a1), 2):
  87                 let_env.set(a1[i], EVAL(a1[i+1], let_env))
  88             ast = a2
  89             env = let_env # Continue loop (TCO)
  90         elif u"quote" == a0sym:
  91             return ast[1]
  92         elif u"quasiquoteexpand" == a0sym:
  93             return quasiquote(ast[1])
  94         elif u"quasiquote" == a0sym:
  95             ast = quasiquote(ast[1]) # Continue loop (TCO)
  96         elif u"do" == a0sym:
  97             if len(ast) == 0:
  98                 return nil
  99             elif len(ast) > 1:
 100                 eval_ast(ast.slice2(1, len(ast)-1), env)
 101             ast = ast[-1] # Continue loop (TCO)
 102         elif u"if" == a0sym:
 103             a1, a2 = ast[1], ast[2]
 104             cond = EVAL(a1, env)
 105             if cond is nil or cond is false:
 106                 if len(ast) > 3: ast = ast[3] # Continue loop (TCO)
 107                 else:            return nil
 108             else:
 109                 ast = a2 # Continue loop (TCO)
 110         elif u"fn*" == a0sym:
 111             a1, a2 = ast[1], ast[2]
 112             return MalFunc(None, a2, env, a1, EVAL)
 113         else:
 114             el = eval_ast(ast, env)
 115             f = el.values[0]
 116             if isinstance(f, MalFunc):
 117                 if f.ast:
 118                     ast = f.ast
 119                     env = f.gen_env(el.rest()) # Continue loop (TCO)
 120                 else:
 121                     return f.apply(el.rest())
 122             else:
 123                 raise Exception("%s is not callable" % f)
 124
 125 # print
 126 def PRINT(exp):
 127     return printer._pr_str(exp)
 128
 129 # repl
 130 class MalEval(MalFunc):
 131     def apply(self, args):
 132         return self.EvalFunc(args[0], self.env)
 133
 134 def entry_point(argv):
 135     repl_env = Env()
 136     def REP(str, env):
 137         return PRINT(EVAL(READ(str), env))
 138
 139     # core.py: defined using python
 140     for k, v in core.ns.items():
 141         repl_env.set(_symbol(unicode(k)), MalFunc(v))
 142     repl_env.set(types._symbol(u'eval'),
 143                  MalEval(None, env=repl_env, EvalFunc=EVAL))
 144     mal_args = []
 145     if len(argv) >= 3:
 146         for a in argv[2:]: mal_args.append(MalStr(unicode(a)))
 147     repl_env.set(_symbol(u'*ARGV*'), MalList(mal_args))
 148
 149     # core.mal: defined using the language itself
 150     REP("(def! not (fn* (a) (if a false true)))", repl_env)
 151     REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \"\nnil)\")))))", repl_env)
 152
 153     if len(argv) >= 2:
 154         REP('(load-file "' + argv[1] + '")', repl_env)
 155         return 0
 156
 157     while True:
 158         try:
 159             line = mal_readline.readline("user> ")
 160             if line == "": continue
 161             print(REP(line, repl_env))
 162         except EOFError as e:
 163             break
 164         except reader.Blank:
 165             continue
 166         except types.MalException as e:
 167             print(u"Error: %s" % printer._pr_str(e.object, False))
 168         except Exception as e:
 169             print("Error: %s" % e)
 170             #print("".join(traceback.format_exception(*sys.exc_info())))
 171     return 0
 172
 173 # _____ Define and setup target ___
 174 def target(*args):
 175     return entry_point
 176
 177 # Just run entry_point if not RPython compilation
 178 import sys
 179 if not sys.argv[0].endswith('rpython'):
 180     entry_point(sys.argv)