rpython/step4_if_fn_do.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 eval_ast(ast, env):
  17     if types._symbol_Q(ast):
  18         assert isinstance(ast, MalSym)
  19         return env.get(ast)
  20     elif types._list_Q(ast):
  21         res = []
  22         for a in ast.values:
  23             res.append(EVAL(a, env))
  24         return MalList(res)
  25     elif types._vector_Q(ast):
  26         res = []
  27         for a in ast.values:
  28             res.append(EVAL(a, env))
  29         return MalVector(res)
  30     elif types._hash_map_Q(ast):
  31         new_dct = {}
  32         for k in ast.dct.keys():
  33             new_dct[k] = EVAL(ast.dct[k], env)
  34         return MalHashMap(new_dct)
  35     else:
  36         return ast  # primitive value, return unchanged
  37
  38 def EVAL(ast, env):
  39         #print("EVAL %s" % printer._pr_str(ast))
  40         if not types._list_Q(ast):
  41             return eval_ast(ast, env)
  42
  43         # apply list
  44         if len(ast) == 0: return ast
  45         a0 = ast[0]
  46         if isinstance(a0, MalSym):
  47             a0sym = a0.value
  48         else:
  49             a0sym = u"__<*fn*>__"
  50
  51         if u"def!" == a0sym:
  52             a1, a2 = ast[1], ast[2]
  53             res = EVAL(a2, env)
  54             return env.set(a1, res)
  55         elif u"let*" == a0sym:
  56             a1, a2 = ast[1], ast[2]
  57             let_env = Env(env)
  58             for i in range(0, len(a1), 2):
  59                 let_env.set(a1[i], EVAL(a1[i+1], let_env))
  60             return EVAL(a2, let_env)
  61         elif u"do" == a0sym:
  62             el = eval_ast(ast.rest(), env)
  63             return el.values[-1]
  64         elif u"if" == a0sym:
  65             a1, a2 = ast[1], ast[2]
  66             cond = EVAL(a1, env)
  67             if cond is nil or cond is false:
  68                 if len(ast) > 3: return EVAL(ast[3], env)
  69                 else:            return nil
  70             else:
  71                 return EVAL(a2, env)
  72         elif u"fn*" == a0sym:
  73             a1, a2 = ast[1], ast[2]
  74             return MalFunc(None, a2, env, a1, EVAL)
  75         else:
  76             el = eval_ast(ast, env)
  77             f = el.values[0]
  78             if isinstance(f, MalFunc):
  79                 return f.apply(el.rest())
  80             else:
  81                 raise Exception("%s is not callable" % f)
  82
  83 # print
  84 def PRINT(exp):
  85     return printer._pr_str(exp)
  86
  87 # repl
  88 def entry_point(argv):
  89     repl_env = Env()
  90     def REP(str, env):
  91         return PRINT(EVAL(READ(str), env))
  92
  93     # core.py: defined using python
  94     for k, v in core.ns.items():
  95         repl_env.set(_symbol(unicode(k)), MalFunc(v))
  96
  97     # core.mal: defined using the language itself
  98     REP("(def! not (fn* (a) (if a false true)))", repl_env)
  99
 100     while True:
 101         try:
 102             line = mal_readline.readline("user> ")
 103             if line == "": continue
 104             print(REP(line, repl_env))
 105         except EOFError as e:
 106             break
 107         except reader.Blank:
 108             continue
 109         except types.MalException as e:
 110             print(u"Error: %s" % printer._pr_str(e.object, False))
 111         except Exception as e:
 112             print("Error: %s" % e)
 113             #print("".join(traceback.format_exception(*sys.exc_info())))
 114     return 0
 115
 116 # _____ Define and setup target ___
 117 def target(*args):
 118     return entry_point
 119
 120 # Just run entry_point if not RPython compilation
 121 import sys
 122 if not sys.argv[0].endswith('rpython'):
 123     entry_point(sys.argv)