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lis.py: added 'define' procedure short form

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This commit is contained in:
Luciano Ramalho 2021-06-09 23:27:42 -03:00
parent 0cbb0c557c
commit e5173fb72b
1 changed files with 10 additions and 10 deletions
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20
18-context-mngr/lispy/py3.10/lis.py
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@ -142,22 +142,22 @@ def lispstr(exp: object) -> str:
def evaluate(x: Expression, env: Environment) -> Any:
"Evaluate an expression in an environment."
match x:
case Symbol(var): # variable reference
case Symbol(var): # variable reference
return env[var]
case literal if not isinstance(x, list): # constant literal
case literal if not isinstance(x, list): # constant literal
return literal
case ['quote', exp]: # (quote exp)
case ['quote', exp]: # (quote exp)
return exp
case ['if', test, conseq, alt]: # (if test conseq alt)
case ['if', test, conseq, alt]: # (if test conseq alt)
exp = conseq if evaluate(test, env) else alt
return evaluate(exp, env)
case ['define', Symbol(var), exp]: # (define var exp)
env[var] = evaluate(exp, env)
case ['define', [name, *parms], body]: # (define (fun parm...) body)
env[name] = Procedure(parms, body, env)
case ['lambda', parms, body]: # (lambda (parm...) body)
case ['lambda', parms, body]: # (lambda (parm...) body)
return Procedure(parms, body, env)
case [op, *args]: # (proc arg...)
case ['define', Symbol(var), exp]: # (define var exp)
env[var] = evaluate(exp, env)
case ['define', [name, *parms], body]: # (define (fun parm...) body)
env[name] = Procedure(parms, body, env)
case [op, *args]: # (proc arg...)
proc = evaluate(op, env)
values = (evaluate(arg, env) for arg in args)
return proc(*values)