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ea81a8087b
- types: low-level mapping to the implementation language. - core: functions on types that are exposed directly to mal. - printer: implementation called by pr-str, str, prn, println. - env: the environment implementation - Also, unindent all TCO while loops so that the diff of step4 and step5 are minimized.
62 lines
1.5 KiB
Python
62 lines
1.5 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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# 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 eval_ast(ast, env):
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if types._symbol_Q(ast):
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try:
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return env[ast]
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except:
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raise Exception("'" + ast + "' not found")
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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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#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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el = eval_ast(ast, env)
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f = el[0]
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return f(*el[1:])
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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 = {}
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def REP(str):
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return PRINT(EVAL(READ(str), repl_env))
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repl_env['+'] = lambda a,b: a+b
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repl_env['-'] = lambda a,b: a-b
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repl_env['*'] = lambda a,b: a*b
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repl_env['/'] = lambda a,b: a/b
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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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