Feat(corelib): IntoIterator doc/tests, iter::traits::collect module

[julio4]

• Add IntoIterator documentation
• Add IntoIterator tests
• Moved IntoIterator from crate::iter::traits::iterator in new module crate::iter::traits::collect. This is to keep the definitions/impls of similar traits for converting collections to/from iterators at the same place (I also implemented FromIterator that depends on this PR), similar to rust standard lib.
• Changed IntoIterator::into_iter return to Self::IntoIter for consistency

[reviewable-StarkWare]

This change is 

[enitrat]

Reviewed 10 of 10 files at r1, all commit messages.
Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @julio4)

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corelib/src/iter/traits/collect.cairo line 10 at r1 (raw file):

/// with Cairo's `for` loop syntax](crate::iter#for-loops-and-intoiterator).
///
/// See also: [`FromIterator`].

IntoIterator ?

Code quote:

See also: [`FromIterator`].

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corelib/src/iter/traits/collect.cairo line 67 at r1 (raw file):

/// // ... and then turn it into an Iterator:
/// let mut n = 0;
/// for i in c.into_iter() {

do you need an explicit into_iter ?

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corelib/src/iter/traits/collect.cairo line 71 at r1 (raw file):

///     n += 1;
/// };
/// ```

would be nice to add the doc about using IntoIterator as a trait bound. same example applies

[julio4]

Reviewable status: 8 of 10 files reviewed, 3 unresolved discussions (waiting on @enitrat)

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corelib/src/iter/traits/collect.cairo line 10 at r1 (raw file):

Previously, enitrat (Mathieu) wrote…

IntoIterator ?

Sorry, didn't push the implementation of FromIterator yet, just need to add tests. I'll remove this for now

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corelib/src/iter/traits/collect.cairo line 67 at r1 (raw file):

Previously, enitrat (Mathieu) wrote…

do you need an explicit into_iter ?

No not in for loops, good catch

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corelib/src/iter/traits/collect.cairo line 71 at r1 (raw file):
Do you mean the collect_as_strings function? It's a bit more tricky to implement now as map and collect is not yet merged in main. The current implementation might be a bit complex/verbose for an example due to IntoIterator/Iterator Item bounds:

fn collect_as_strings<
    T,
    impl TIntoIterator: IntoIterator<T>,
    +core::fmt::Debug<TIntoIterator::Iterator::<TIntoIterator::IntoIter>::Item>,
    +Drop<TIntoIterator::Iterator::<TIntoIterator::IntoIter>::Item>,
    +Drop<TIntoIterator::IntoIter>,
>(
    collection: T,
) -> Array<ByteArray> {
    let mut res = array![];
    for item in collection {
        res.append(format!("{item:?}"));
    };
    res
}

#[test]
fn test_into_iter_trait_bound() {
    let arr = array![0, 1, 2];
    let res = collect_as_strings(arr);
    assert_eq!(res, array!["0", "1", "2"]);
}

[orizi]

Reviewable status: 8 of 10 files reviewed, 4 unresolved discussions (waiting on @enitrat and @julio4)

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corelib/src/iter/traits/collect.cairo line 10 at r1 (raw file):

Previously, julio4 (Julio) wrote…

Sorry, didn't push the implementation of FromIterator yet, just need to add tests. I'll remove this for now

more so - please do not add it in this PR - it is already large enough as it is.

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corelib/src/array.cairo line 845 at r2 (raw file):

    type IntoIter = ArrayIter<T>;
    #[inline]
    fn into_iter(self: Array<T>) -> Self::IntoIter {

unrelated - revert.

Code quote:

    type IntoIter = SpanIter<T>;
    #[inline]
    fn into_iter(self: Span<T>) -> Self::IntoIter {
        SpanIter { span: self }
    }
}

impl ArrayIntoIterator<T> of crate::iter::IntoIterator<Array<T>> {
    type IntoIter = ArrayIter<T>;
    #[inline]
    fn into_iter(self: Array<T>) -> Self::IntoIter {

[orizi]

Reviewable status: 8 of 10 files reviewed, 5 unresolved discussions (waiting on @enitrat and @julio4)

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corelib/src/ops/range.cairo line 139 at r2 (raw file):

> of IntoIterator<Range<T>> {
    type IntoIter = internal::IntRange<T>;
    #[inline]

unrelated - revert.

Code quote:

    type IntoIter = RangeIterator<T>;
    fn into_iter(self: Range<T>) -> Self::IntoIter {
        let start = self.start;
        let end = self.end;
    T, +Copy<T>, +Drop<T>, +SierraIntRangeSupport<T>,
> of IntoIterator<Range<T>> {
    type IntoIter = internal::IntRange<T>;
    #[inline]

[julio4]

Reviewable status: 8 of 10 files reviewed, 5 unresolved discussions (waiting on @enitrat and @orizi)

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corelib/src/array.cairo line 845 at r2 (raw file):

Previously, orizi wrote…

unrelated - revert.

Done.

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corelib/src/iter/traits/collect.cairo line 10 at r1 (raw file):

Previously, orizi wrote…

more so - please do not add it in this PR - it is already large enough as it is.

Yes, will open after this one is merged!

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corelib/src/ops/range.cairo line 139 at r2 (raw file):

Previously, orizi wrote…

unrelated - revert.

Done.

[orizi]

Reviewed 1 of 10 files at r1, 2 of 2 files at r3, all commit messages.
Reviewable status: 8 of 10 files reviewed, 6 unresolved discussions (waiting on @enitrat and @julio4)

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corelib/src/iter/traits/collect.cairo line 84 at r3 (raw file):

    /// ```
    /// let v = array![1, 2, 3];
    /// let mut iter = v.into_iter();

consider doing these more often

Suggestion:

    /// let mut iter = array![1, 2, 3].into_iter();

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corelib/src/test/iter_test.cairo line 1 at r3 (raw file):

use crate::iter::IntoIterator;

in prelude now.

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corelib/src/test/iter_test.cairo line 1 at r3 (raw file):

use crate::iter::IntoIterator;

i don't understand what is tested here.

if it is the for it is in for_test.cairo
if it is the array it is tested in array_test.cairo

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corelib/src/test/iter_test.cairo line 11 at r3 (raw file):

    assert_eq!(Option::Some(2), iter.next());
    assert_eq!(Option::Some(3), iter.next());
    assert_eq!(Option::None, iter.next());

Suggestion:

    let mut iter = array![1, 2, 3].into_iter();
    assert_eq!(Option::Some(1), iter.next());
    assert_eq!(Option::Some(2), iter.next());
    assert_eq!(Option::Some(3), iter.next());
    assert_eq!(Option::None, iter.next());

[enitrat]

Reviewable status: 8 of 10 files reviewed, 3 unresolved discussions (waiting on @julio4)

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corelib/src/iter/traits/collect.cairo line 71 at r1 (raw file):

Previously, julio4 (Julio) wrote…

Do you mean the collect_as_strings function? It's a bit more tricky to implement now as map and collect is not yet merged in main. The current implementation might be a bit complex/verbose for an example due to IntoIterator/Iterator Item bounds:

fn collect_as_strings<
    T,
    impl TIntoIterator: IntoIterator<T>,
    +core::fmt::Debug<TIntoIterator::Iterator::<TIntoIterator::IntoIter>::Item>,
    +Drop<TIntoIterator::Iterator::<TIntoIterator::IntoIter>::Item>,
    +Drop<TIntoIterator::IntoIter>,
>(
    collection: T,
) -> Array<ByteArray> {
    let mut res = array![];
    for item in collection {
        res.append(format!("{item:?}"));
    };
    res
}

#[test]
fn test_into_iter_trait_bound() {
    let arr = array![0, 1, 2];
    let res = collect_as_strings(arr);
    assert_eq!(res, array!["0", "1", "2"]);
}

ok, i'll note this on the side

[julio4]

Reviewable status: 8 of 10 files reviewed, 3 unresolved discussions (waiting on @enitrat and @orizi)

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corelib/src/test/iter_test.cairo line 1 at r3 (raw file):

Previously, orizi wrote…

in prelude now.

Done.

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corelib/src/test/iter_test.cairo line 1 at r3 (raw file):

Previously, orizi wrote…

i don't understand what is tested here.

if it is the for it is in for_test.cairo
if it is the array it is tested in array_test.cairo

I wanted to test a custom implementation of IntoIterator, same as shown in the documentation.
We can remove it

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corelib/src/test/iter_test.cairo line 11 at r3 (raw file):

    assert_eq!(Option::Some(2), iter.next());
    assert_eq!(Option::Some(3), iter.next());
    assert_eq!(Option::None, iter.next());

Done.

[orizi]

Reviewable status: 8 of 10 files reviewed, 3 unresolved discussions (waiting on @enitrat and @julio4)

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corelib/src/test/iter_test.cairo line 1 at r3 (raw file):

Previously, julio4 (Julio) wrote…

I wanted to test a custom implementation of IntoIterator, same as shown in the documentation.
We can remove it

but all implementations are custom i just don't see what this adds.

more so for the first test - which is just a duplication of array iterator tests.

[julio4]

Reviewable status: 7 of 10 files reviewed, 3 unresolved discussions (waiting on @enitrat and @orizi)

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corelib/src/test/iter_test.cairo line 1 at r3 (raw file):

Previously, orizi wrote…

but all implementations are custom i just don't see what this adds.

more so for the first test - which is just a duplication of array iterator tests.

I see, so we'll add tests only for specific features on Iterator not for testing default trait impls.
I removed iter_tests.

[orizi]

Reviewed all commit messages.
Reviewable status: 7 of 10 files reviewed, 4 unresolved discussions (waiting on @enitrat and @julio4)

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a discussion (no related file):
Can you explain the logic of IntoIterator being in collect module?

[julio4]

Previously, orizi wrote…

Can you explain the logic of IntoIterator being in collect module?

I followed the rust standard library.
I agree that collect is not the perfect name, as it's more like traits that allow conversion of type from/to Iterator.
But because Cairo is strongly following rust it's easier to keep track of what is implemented or not when the modules organization is similar.

[orizi]

Reviewed 4 of 10 files at r1, 1 of 2 files at r4, 2 of 2 files at r5.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @julio4)

[orizi]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @julio4)

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

[gilbens-starkware]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @julio4)