feat(corelib): OptionTrait::filter

[hudem1]

I suggest the addition of OptionTrait::filter method that:

returns [None] if the option is [None], otherwise calls predicate with the wrapped value and returns:

• [Some(t)] if predicate returns true (where t is the wrapped value)
• [None] if predicate returns false.

let is_even = |x: u32| -> bool {
    x % 2 == 0
};

assert!(Option::None.filter(is_even) == Option::None);
assert!(Option::Some(3).filter(is_even) == Option::None);
assert!(Option::Some(4).filter(is_even) == Option::Some(4));

[reviewable-StarkWare]

This change is 

[orizi]

Reviewed 2 of 2 files at r1.
Reviewable status: all files reviewed (commit messages unreviewed), 1 unresolved discussion (waiting on @hudem1)

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corelib/src/option.cairo line 808 at r1 (raw file):

    }

    fn filter<P, +core::ops::FnOnce<P, (T,)>[Output: bool], +Drop<T>, +Drop<P>, +Copy<T>>(

Suggestion:

    fn filter<P, +core::ops::FnOnce<P, (@T,)>[Output: bool], +Destruct<T>, +Destruct<P>>(

[hudem1]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @orizi)

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corelib/src/option.cairo line 808 at r1 (raw file):

    }

    fn filter<P, +core::ops::FnOnce<P, (T,)>[Output: bool], +Drop<T>, +Drop<P>, +Copy<T>>(

Done.

[orizi]

Reviewed 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @hudem1)

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a discussion (no related file):
@gilbens-starkware

[orizi]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @hudem1)

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a discussion (no related file):

Previously, orizi wrote…

@gilbens-starkware

@ilyalesokhin-starkware for 2nd eye.

[gilbens-starkware]

Reviewed 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @hudem1)