rpython/step3_env.py

   1 #import sys, traceback
   2 import mal_readline
   3 import mal_types as types
   4 from mal_types import (MalSym, MalInt, MalStr,
   5                        _symbol, _keywordu,
   6                        MalList, _list, MalVector, MalHashMap, MalFunc)
   7 import reader, printer
   8 from env import Env
   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         res = []
  26         for a in ast.values:
  27             res.append(EVAL(a, env))
  28         return MalVector(res)
  29     elif types._hash_map_Q(ast):
  30         new_dct = {}
  31         for k in ast.dct.keys():
  32             new_dct[k] = EVAL(ast.dct[k], env)
  33         return MalHashMap(new_dct)
  34     else:
  35         return ast  # primitive value, return unchanged
  36
  37 def EVAL(ast, env):
  38         #print("EVAL %s" % printer._pr_str(ast))
  39         if not types._list_Q(ast):
  40             return eval_ast(ast, env)
  41
  42         # apply list
  43         if len(ast) == 0: return ast
  44         a0 = ast[0]
  45         if not isinstance(a0, MalSym):
  46             raise Exception("attempt to apply on non-symbol")
  47
  48         if u"def!" == a0.value:
  49             a1, a2 = ast[1], ast[2]
  50             res = EVAL(a2, env)
  51             return env.set(a1, res)
  52         elif u"let*" == a0.value:
  53             a1, a2 = ast[1], ast[2]
  54             let_env = Env(env)
  55             for i in range(0, len(a1), 2):
  56                 let_env.set(a1[i], EVAL(a1[i+1], let_env))
  57             return EVAL(a2, let_env)
  58         else:
  59             el = eval_ast(ast, env)
  60             f = el.values[0]
  61             if isinstance(f, MalFunc):
  62                 return f.apply(el.values[1:])
  63             else:
  64                 raise Exception("%s is not callable" % f)
  65
  66 # print
  67 def PRINT(exp):
  68     return printer._pr_str(exp)
  69
  70 # repl
  71 repl_env = Env()
  72 def REP(str, env):
  73     return PRINT(EVAL(READ(str), env))
  74
  75 def plus(args):
  76     a, b = args[0], args[1]
  77     assert isinstance(a, MalInt)
  78     assert isinstance(b, MalInt)
  79     return MalInt(a.value+b.value)
  80 def minus(args):
  81     a, b = args[0], args[1]
  82     assert isinstance(a, MalInt)
  83     assert isinstance(b, MalInt)
  84     return MalInt(a.value-b.value)
  85 def multiply(args):
  86     a, b = args[0], args[1]
  87     assert isinstance(a, MalInt)
  88     assert isinstance(b, MalInt)
  89     return MalInt(a.value*b.value)
  90 def divide(args):
  91     a, b = args[0], args[1]
  92     assert isinstance(a, MalInt)
  93     assert isinstance(b, MalInt)
  94     return MalInt(int(a.value/b.value))
  95 repl_env.set(_symbol(u'+'), MalFunc(plus))
  96 repl_env.set(_symbol(u'-'), MalFunc(minus))
  97 repl_env.set(_symbol(u'*'), MalFunc(multiply))
  98 repl_env.set(_symbol(u'/'), MalFunc(divide))
  99
 100 def entry_point(argv):
 101     while True:
 102         try:
 103             line = mal_readline.readline("user> ")
 104             if line == "": continue
 105             print(REP(line, repl_env))
 106         except EOFError as e:
 107             break
 108         except reader.Blank:
 109             continue
 110         except types.MalException as e:
 111             print(u"Error: %s" % printer._pr_str(e.object, False))
 112         except Exception as e:
 113             print("Error: %s" % e)
 114             #print("".join(traceback.format_exception(*sys.exc_info())))
 115     return 0
 116
 117 # _____ Define and setup target ___
 118 def target(*args):
 119     return entry_point
 120
 121 # Just run entry_point if not RPython compilation
 122 import sys
 123 if not sys.argv[0].endswith('rpython'):
 124     entry_point(sys.argv)