mirror of
https://github.com/kanaka/mal.git
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125 lines
3.6 KiB
Python
125 lines
3.6 KiB
Python
import sys, traceback
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import mal_readline
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import mal_types as types
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import reader, printer
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from env import Env
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import core
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# read
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def READ(str):
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return reader.read_str(str)
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# eval
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def is_pair(x):
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return types._sequential_Q(x) and len(x) > 0
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def quasiquote(ast):
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if not is_pair(ast):
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return types._list(types._symbol("quote"),
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ast)
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elif ast[0] == 'unquote':
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return ast[1]
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elif is_pair(ast[0]) and ast[0][0] == 'splice-unquote':
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return types._list(types._symbol("concat"),
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ast[0][1],
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quasiquote(ast[1:]))
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else:
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return types._list(types._symbol("cons"),
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quasiquote(ast[0]),
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quasiquote(ast[1:]))
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def eval_ast(ast, env):
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if types._symbol_Q(ast):
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return env.get(ast)
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elif types._list_Q(ast):
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return types._list(*map(lambda a: EVAL(a, env), ast))
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elif types._vector_Q(ast):
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return types._vector(*map(lambda a: EVAL(a, env), ast))
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elif types._hash_map_Q(ast):
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keyvals = []
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for k in ast.keys():
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keyvals.append(EVAL(k, env))
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keyvals.append(EVAL(ast[k], env))
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return types._hash_map(*keyvals)
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else:
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return ast # primitive value, return unchanged
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def EVAL(ast, env):
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while True:
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#print("EVAL %s" % ast)
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if not types._list_Q(ast):
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return eval_ast(ast, env)
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# apply list
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if len(ast) == 0: return ast
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a0 = ast[0]
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if "def!" == a0:
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a1, a2 = ast[1], ast[2]
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res = EVAL(a2, env)
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return env.set(a1, res)
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elif "let*" == a0:
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a1, a2 = ast[1], ast[2]
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let_env = Env(env)
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for i in range(0, len(a1), 2):
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let_env.set(a1[i], EVAL(a1[i+1], let_env))
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return EVAL(a2, let_env)
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elif "quote" == a0:
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return ast[1]
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elif "quasiquote" == a0:
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return EVAL(quasiquote(ast[1]), env)
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elif "do" == a0:
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eval_ast(ast[1:-1], env)
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ast = ast[-1]
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# Continue loop (TCO)
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elif "if" == a0:
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a1, a2 = ast[1], ast[2]
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cond = EVAL(a1, env)
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if cond is None or cond is False:
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if len(ast) > 3: ast = ast[3]
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else: ast = None
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else:
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ast = a2
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# Continue loop (TCO)
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elif "fn*" == a0:
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a1, a2 = ast[1], ast[2]
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return types._function(EVAL, Env, a2, env, a1)
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else:
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el = eval_ast(ast, env)
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f = el[0]
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if hasattr(f, '__ast__'):
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ast = f.__ast__
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env = f.__gen_env__(el[1:])
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else:
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return f(*el[1:])
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# print
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def PRINT(exp):
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return printer._pr_str(exp)
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# repl
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repl_env = Env()
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def REP(str):
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return PRINT(EVAL(READ(str), repl_env))
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# core.py: defined using python
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for k, v in core.ns.items(): repl_env.set(k, v)
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repl_env.set('eval', lambda ast: EVAL(ast, repl_env))
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# core.mal: defined using the language itself
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REP("(def! not (fn* (a) (if a false true)))")
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REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))")
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if len(sys.argv) >= 2:
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REP('(load-file "' + sys.argv[1] + '")')
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else:
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while True:
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try:
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line = mal_readline.readline("user> ")
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if line == None: break
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if line == "": continue
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print(REP(line))
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except reader.Blank: continue
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except Exception as e:
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print("".join(traceback.format_exception(*sys.exc_info())))
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