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import sys, traceback
import mal_readline
import mal_types as types
import reader, printer
from env import Env
import core
# read
def READ(str):
return reader.read_str(str)
# eval
def is_pair(x):
return types._sequential_Q(x) and len(x) > 0
def quasiquote(ast):
if not is_pair(ast):
return types._list(types._symbol("quote"),
ast)
elif ast[0] == 'unquote':
return ast[1]
elif is_pair(ast[0]) and ast[0][0] == 'splice-unquote':
return types._list(types._symbol("concat"),
ast[0][1],
quasiquote(ast[1:]))
else:
return types._list(types._symbol("cons"),
quasiquote(ast[0]),
quasiquote(ast[1:]))
def is_macro_call(ast, env):
return (types._list_Q(ast) and
types._symbol_Q(ast[0]) and
env.find(ast[0]) and
hasattr(env.get(ast[0]), '_ismacro_'))
def macroexpand(ast, env):
while is_macro_call(ast, env):
mac = env.get(ast[0])
ast = macroexpand(mac(*ast[1:]), env)
return ast
def eval_ast(ast, env):
if types._symbol_Q(ast):
return env.get(ast)
elif types._list_Q(ast):
return types._list(*map(lambda a: EVAL(a, env), ast))
elif types._vector_Q(ast):
return types._vector(*map(lambda a: EVAL(a, env), ast))
elif types._hash_map_Q(ast):
keyvals = []
for k in ast.keys():
keyvals.append(EVAL(k, env))
keyvals.append(EVAL(ast[k], env))
return types._hash_map(*keyvals)
else:
return ast # primitive value, return unchanged
def EVAL(ast, env):
while True:
#print("EVAL %s" % printer._pr_str(ast))
if not types._list_Q(ast):
return eval_ast(ast, env)
# apply list
ast = macroexpand(ast, env)
if not types._list_Q(ast): return ast
if len(ast) == 0: return ast
a0 = ast[0]
if "def!" == a0:
a1, a2 = ast[1], ast[2]
res = EVAL(a2, env)
return env.set(a1, res)
elif "let*" == a0:
a1, a2 = ast[1], ast[2]
let_env = Env(env)
for i in range(0, len(a1), 2):
let_env.set(a1[i], EVAL(a1[i+1], let_env))
ast = a2
env = let_env
# Continue loop (TCO)
elif "quote" == a0:
return ast[1]
elif "quasiquote" == a0:
ast = quasiquote(ast[1]);
# Continue loop (TCO)
elif 'defmacro!' == a0:
func = EVAL(ast[2], env)
func._ismacro_ = True
return env.set(ast[1], func)
elif 'macroexpand' == a0:
return macroexpand(ast[1], env)
elif "py!*" == a0:
if sys.version_info[0] >= 3:
exec(compile(ast[1], '', 'single'), globals())
else:
exec(compile(ast[1], '', 'single') in globals())
return None
elif "py*" == a0:
return eval(ast[1])
elif "." == a0:
el = eval_ast(ast[2:], env)
f = eval(ast[1])
return f(*el)
elif "try*" == a0:
a1, a2 = ast[1], ast[2]
if a2[0] == "catch*":
try:
return EVAL(a1, env);
except Exception as exc:
exc = exc.args[0]
catch_env = Env(env, [a2[1]], [exc])
return EVAL(a2[2], catch_env)
else:
return EVAL(a1, env);
elif "do" == a0:
eval_ast(ast[1:-1], env)
ast = ast[-1]
# Continue loop (TCO)
elif "if" == a0:
a1, a2 = ast[1], ast[2]
cond = EVAL(a1, env)
if cond is None or cond is False:
if len(ast) > 3: ast = ast[3]
else: ast = None
else:
ast = a2
# Continue loop (TCO)
elif "fn*" == a0:
a1, a2 = ast[1], ast[2]
return types._function(EVAL, Env, a2, env, a1)
else:
el = eval_ast(ast, env)
f = el[0]
if hasattr(f, '__ast__'):
ast = f.__ast__
env = f.__gen_env__(el[1:])
else:
return f(*el[1:])
# print
def PRINT(exp):
return printer._pr_str(exp)
# repl
repl_env = Env()
def REP(str):
return PRINT(EVAL(READ(str), repl_env))
# core.py: defined using python
for k, v in core.ns.items(): repl_env.set(k, v)
repl_env.set('eval', lambda ast: EVAL(ast, repl_env))
repl_env.set('*ARGV*', types._list(*sys.argv[2:]))
# core.mal: defined using the language itself
REP("(def! *host-language* \"python\")")
REP("(def! not (fn* (a) (if a false true)))")
REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))")
REP("(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))")
REP("(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))")
if len(sys.argv) >= 2:
REP('(load-file "' + sys.argv[1] + '")')
sys.exit(0)
# repl loop
REP("(println (str \"Mal [\" *host-language* \"]\"))")
while True:
try:
line = mal_readline.readline("user> ")
if line == None: break
if line == "": continue
print(REP(line))
except reader.Blank: continue
except Exception as e:
print("".join(traceback.format_exception(*sys.exc_info())))
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