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mirror of https://github.com/kanaka/mal.git synced 2024-10-27 14:52:16 +03:00
mal/impls/python/step2_eval.py
Joel Martin 8a19f60386 Move implementations into impls/ dir
- Reorder README to have implementation list after "learning tool"
  bullet.

- This also moves tests/ and libs/ into impls. It would be preferrable
  to have these directories at the top level.  However, this causes
  difficulties with the wasm implementations which need pre-open
  directories and have trouble with paths starting with "../../". So
  in lieu of that, symlink those directories to the top-level.

- Move the run_argv_test.sh script into the tests directory for
  general hygiene.
2020-02-10 23:50:16 -06:00

65 lines
1.6 KiB
Python

import sys, traceback
import mal_readline
import mal_types as types
import reader, printer
# read
def READ(str):
return reader.read_str(str)
# eval
def eval_ast(ast, env):
if types._symbol_Q(ast):
try:
return env[ast]
except:
raise Exception("'" + ast + "' not found")
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):
#print("EVAL %s" % printer._pr_str(ast))
if not types._list_Q(ast):
return eval_ast(ast, env)
# apply list
if len(ast) == 0: return ast
el = eval_ast(ast, env)
f = el[0]
return f(*el[1:])
# print
def PRINT(exp):
return printer._pr_str(exp)
# repl
repl_env = {}
def REP(str):
return PRINT(EVAL(READ(str), repl_env))
repl_env['+'] = lambda a,b: a+b
repl_env['-'] = lambda a,b: a-b
repl_env['*'] = lambda a,b: a*b
repl_env['/'] = lambda a,b: int(a/b)
# repl loop
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())))