rpython/step5_tco.py

   1 import sys, traceback
   2 import mal_readline
   3 import mal_types as types
   4 from mal_types import (MalSym, MalInt, MalStr, nil, true, false,
   5                        _symbol, _keywordu, MalList, _list, MalFunc)
   6 import reader, printer
   7 from env import Env
   8 import core
   9
  10 # read
  11 def READ(str):
  12     return reader.read_str(str)
  13
  14 # eval
  15 def eval_ast(ast, env):
  16     if types._symbol_Q(ast):
  17         assert isinstance(ast, MalSym)
  18         return env.get(ast)
  19     elif types._list_Q(ast):
  20         res = []
  21         for a in ast.values:
  22             res.append(EVAL(a, env))
  23         return MalList(res)
  24 ##    elif types._vector_Q(ast):
  25 ##        return types._vector(*map(lambda a: EVAL(a, env), ast))
  26 ##    elif types._hash_map_Q(ast):
  27 ##        keyvals = []
  28 ##        for k in ast.keys():
  29 ##            keyvals.append(EVAL(k, env))
  30 ##            keyvals.append(EVAL(ast[k], env))
  31 ##        return types._hash_map(*keyvals)
  32     else:
  33         return ast  # primitive value, return unchanged
  34
  35 def EVAL(ast, env):
  36     while True:
  37         #print("EVAL %s" % printer._pr_str(ast))
  38         if not types._list_Q(ast):
  39             return eval_ast(ast, env)
  40
  41         # apply list
  42         if len(ast) == 0: return ast
  43         a0 = ast[0]
  44         if isinstance(a0, MalSym):
  45             a0sym = a0.value
  46         else:
  47             a0sym = u"__<*fn*>__"
  48
  49         if u"def!" == a0sym:
  50             a1, a2 = ast[1], ast[2]
  51             res = EVAL(a2, env)
  52             return env.set(a1, res)
  53         elif u"let*" == a0sym:
  54             a1, a2 = ast[1], ast[2]
  55             let_env = Env(env)
  56             for i in range(0, len(a1), 2):
  57                 let_env.set(a1[i], EVAL(a1[i+1], let_env))
  58             ast = a2
  59             env = let_env # Continue loop (TCO)
  60         elif u"do" == a0sym:
  61             if len(ast) == 0:
  62                 return nil
  63             elif len(ast) > 1:
  64                 eval_ast(ast.slice2(1, len(ast)-1), env)
  65             ast = ast[-1] # Continue loop (TCO)
  66         elif u"if" == a0sym:
  67             a1, a2 = ast[1], ast[2]
  68             cond = EVAL(a1, env)
  69             if cond is nil or cond is false:
  70                 if len(ast) > 3: ast = ast[3] # Continue loop (TCO)
  71                 else:            return nil
  72             else:
  73                 ast = a2 # Continue loop (TCO)
  74         elif u"fn*" == a0sym:
  75             a1, a2 = ast[1], ast[2]
  76             return MalFunc(None, a2, env, a1, EVAL)
  77         else:
  78             el = eval_ast(ast, env)
  79             f = el.values[0]
  80             if isinstance(f, MalFunc):
  81                 if f.ast:
  82                     ast = f.ast
  83                     env = f.gen_env(el.rest()) # Continue loop (TCO)
  84                 else:
  85                     return f.apply(el.rest())
  86             else:
  87                 raise Exception("%s is not callable" % f)
  88
  89 # print
  90 def PRINT(exp):
  91     return printer._pr_str(exp)
  92
  93 # repl
  94 def entry_point(argv):
  95     repl_env = Env()
  96     def REP(str, env):
  97         return PRINT(EVAL(READ(str), env))
  98
  99     # core.py: defined using python
 100     for k, v in core.ns.items():
 101         repl_env.set(_symbol(unicode(k)), MalFunc(v))
 102
 103     # core.mal: defined using the language itself
 104     REP("(def! not (fn* (a) (if a false true)))", repl_env)
 105
 106     while True:
 107         try:
 108             line = mal_readline.readline("user> ")
 109             if line == "": continue
 110             print(REP(line, repl_env))
 111         except EOFError as e:
 112             break
 113         except Exception as e:
 114             print(e)
 115             #print("".join(traceback.format_exception(*sys.exc_info())))
 116     return 0
 117
 118 # _____ Define and setup target ___
 119 def target(*args):
 120     return entry_point
 121
 122 # Just run entry_point if not RPython compilation
 123 import sys
 124 if not sys.argv[0].endswith('rpython'):
 125     entry_point(sys.argv)