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, _symbol, _keywordu,
   5                        MalList, _list, MalVector, MalHashMap, MalFunc)
   6 import reader, printer
   7 from env import Env
   8
   9 # read
  10 def READ(str):
  11     return reader.read_str(str)
  12
  13 # eval
  14 def eval_ast(ast, env):
  15     if types._symbol_Q(ast):
  16         assert isinstance(ast, MalSym)
  17         return env.get(ast)
  18     elif types._list_Q(ast):
  19         res = []
  20         for a in ast.values:
  21             res.append(EVAL(a, env))
  22         return MalList(res)
  23     elif types._vector_Q(ast):
  24         res = []
  25         for a in ast.values:
  26             res.append(EVAL(a, env))
  27         return MalVector(res)
  28     elif types._hash_map_Q(ast):
  29         new_dct = {}
  30         for k in ast.dct.keys():
  31             new_dct[k] = EVAL(ast.dct[k], env)
  32         return MalHashMap(new_dct)
  33     else:
  34         return ast  # primitive value, return unchanged
  35
  36 def EVAL(ast, env):
  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 not isinstance(a0, MalSym):
  45             raise Exception("attempt to apply on non-symbol")
  46
  47         if u"def!" == a0.value:
  48             a1, a2 = ast[1], ast[2]
  49             res = EVAL(a2, env)
  50             return env.set(a1, res)
  51         elif u"let*" == a0.value:
  52             a1, a2 = ast[1], ast[2]
  53             let_env = Env(env)
  54             for i in range(0, len(a1), 2):
  55                 let_env.set(a1[i], EVAL(a1[i+1], let_env))
  56             return EVAL(a2, let_env)
  57         else:
  58             el = eval_ast(ast, env)
  59             f = el.values[0]
  60             if isinstance(f, MalFunc):
  61                 return f.apply(el.values[1:])
  62             else:
  63                 raise Exception("%s is not callable" % f)
  64
  65 # print
  66 def PRINT(exp):
  67     return printer._pr_str(exp)
  68
  69 # repl
  70 repl_env = Env()
  71 def REP(str, env):
  72     return PRINT(EVAL(READ(str), env))
  73
  74 def plus(args):
  75     a, b = args[0], args[1]
  76     assert isinstance(a, MalInt)
  77     assert isinstance(b, MalInt)
  78     return MalInt(a.value+b.value)
  79 def minus(args):
  80     a, b = args[0], args[1]
  81     assert isinstance(a, MalInt)
  82     assert isinstance(b, MalInt)
  83     return MalInt(a.value-b.value)
  84 def multiply(args):
  85     a, b = args[0], args[1]
  86     assert isinstance(a, MalInt)
  87     assert isinstance(b, MalInt)
  88     return MalInt(a.value*b.value)
  89 def divide(args):
  90     a, b = args[0], args[1]
  91     assert isinstance(a, MalInt)
  92     assert isinstance(b, MalInt)
  93     return MalInt(int(a.value/b.value))
  94 repl_env.set(_symbol(u'+'), MalFunc(plus))
  95 repl_env.set(_symbol(u'-'), MalFunc(minus))
  96 repl_env.set(_symbol(u'*'), MalFunc(multiply))
  97 repl_env.set(_symbol(u'/'), MalFunc(divide))
  98
  99 def entry_point(argv):
 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 Exception as e:
 108             print(e)
 109             #print("".join(traceback.format_exception(*sys.exc_info())))
 110     return 0
 111
 112 # _____ Define and setup target ___
 113 def target(*args):
 114     return entry_point
 115
 116 # Just run entry_point if not RPython compilation
 117 import sys
 118 if not sys.argv[0].endswith('rpython'):
 119     entry_point(sys.argv)