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import sys, traceback
import mal_readline
from mal_types import (pr_str, sequential_Q, symbol_Q, coll_Q, list_Q,
vector_Q, hash_map_Q, new_symbol, new_function,
new_list, new_vector, new_hash_map, Env, types_ns)
from reader import (read_str, Blank)
# read
def READ(str):
return read_str(str)
# eval
def is_pair(x):
return sequential_Q(x) and len(x) > 0
def quasiquote(ast):
if not is_pair(ast):
return new_list(new_symbol("quote"), ast)
elif ast[0] == 'unquote':
return ast[1]
elif is_pair(ast[0]) and ast[0][0] == 'splice-unquote':
return new_list(new_symbol("concat"), ast[0][1], quasiquote(ast[1:]))
else:
return new_list(new_symbol("cons"), quasiquote(ast[0]), quasiquote(ast[1:]))
def is_macro_call(ast, env):
return (list_Q(ast) and
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 symbol_Q(ast):
return env.get(ast)
elif list_Q(ast):
return new_list(*map(lambda a: EVAL(a, env), ast))
elif vector_Q(ast):
return new_vector(*map(lambda a: EVAL(a, env), ast))
elif hash_map_Q(ast):
keyvals = []
for k in ast.keys():
keyvals.append(EVAL(k, env))
keyvals.append(EVAL(ast[k], env))
return new_hash_map(*keyvals)
else:
return ast # primitive value, return unchanged
def EVAL(ast, env):
while True:
#print("EVAL %s" % ast)
if not list_Q(ast):
return eval_ast(ast, env)
# apply list
ast = macroexpand(ast, env)
if not 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))
return EVAL(a2, let_env)
elif "quote" == a0:
return ast[1]
elif "quasiquote" == a0:
return EVAL(quasiquote(ast[1]), env)
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:
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 "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 new_function(EVAL, a2, env, a1)
else:
el = eval_ast(ast, env)
f = el[0]
if hasattr(f, '__meta__') and f.__meta__.has_key("exp"):
m = f.__meta__
ast = m['exp']
env = Env(m['env'], m['params'], el[1:])
else:
return f(*el[1:])
# print
def PRINT(exp):
return pr_str(exp)
# repl
repl_env = Env()
def REP(str):
return PRINT(EVAL(READ(str), repl_env))
def _ref(k,v): repl_env.set(k, v)
# Import types functions
for name, val in types_ns.items(): _ref(name, val)
_ref('read-string', read_str)
_ref('eval', lambda ast: EVAL(ast, repl_env))
_ref('slurp', lambda file: open(file).read())
_ref('slurp-do', lambda file: "(do" + open(file).read() + ")")
# Defined using the language itself
REP("(def! not (fn* (a) (if a false true)))")
REP("(def! load-file (fn* (f) (eval (read-string (slurp-do f)))))")
if len(sys.argv) >= 2:
REP('(load-file "' + sys.argv[1] + '")')
else:
while True:
try:
line = mal_readline.readline("user> ")
if line == None: break
if line == "": continue
print(REP(line))
except Blank: continue
except Exception as e:
print "".join(traceback.format_exception(*sys.exc_info()))
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