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