[Python-ideas] unify usage of mutable and immutable objects

语言破碎处 mlet_it_bew at 126.com
Tue Feb 28 13:13:59 EST 2017

> That is simply misspelled for your intent.

Take a look at the following function in Haskell (GHC) Data.Set
    minView :: Set a -> Maybe (a, Set a)
We always want the new set after a immutable set pop().
    "e = a.pop()" is fine for mutable set, but not for immutable case.
    we need "e, a = a.pop()" to update "a".

在 2017-03-01 01:23:54,"David Mertz" <mertz at gnosis.cx> 写道:

On Tue, Feb 28, 2017 at 5:59 AM, 语言破碎处 <mlet_it_bew at 126.com> wrote:

bad example:
    a = set()
    a.add(1)        # return None; "a" changed
    e = a.pop();

That is simply misspelled for your intent.

a = set()
a |= {1}
e = a.pop()


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