This PR does what #9234 regrettably failed to do: actually reintroduce
the signatures of some `Subarray` functions that are now implemented via
slices (see #9017) in order to ensure backward compatibility and
consistency. With this PR, the old interface is restored. As an added
benefit, `Subarray.forIn` is no longer opaque.
An earlier PR (#9017) replaced certain subarray functions such as
`Subarray.foldl` with generic slice functions `Slice.foldl`. For
backward compatibility reasons, This PR reintroduces `Subarray.foldl`
etc. as aliases for the `Slice` versions.
This PR removes the `Subarray`-specific `toArray`, `foldlM` and `foldl`
methods and instead provides these operations on `Std.Slice`, which are
implemented with the `ToIterator` instance of the slice. Calling
`subarray.toArray` etc. still works, since `Subarray` is an abbreviation
for `Slice _`.
Because the benchmarks are not so clear, to be safe, I will merge this
only after the release. In contrast to the ranges, the iteration over
slices is not quite as efficient as the old `Subarray`-specific
implementation, which would require either more optimizations in the
iterator library (special `IteratorLoop` and `IteratorCollect`
implementations) or better unboxing support by the compiler.
This PR adjusts the experimental module system to make `private` the
default visibility modifier in `module`s, introducing `public` as a new
modifier instead. `public section` can be used to revert the default for
an entire section, though this is more intended to ease gradual adoption
of the new semantics such as in `Init` (and soon `Std`) where they
should be replaced by a future decl-by-decl re-review of visibilities.
This PR proves that the default `toList`, `toListRev` and `toArray`
functions on slices can be described in terms of the slice iterator.
Relying on new lemmas for the `uLift` and `attachWith` iterator
combinators, a more concrete description of said functions is given for
`Subarray`.
This PR replaces all usages of `[:]` slice notation in `src` with the
new `[...]` notation in production code, tests and comments. The
underlying implementation of the `Subarray` functions stays the same.
Notation cheat sheet:
* `*...*` is the doubly-unbounded range.
* `*...a` or `*...<a` contains all elements that are less than `a`.
* `*...=a` contains all elements that are less than or equal to `a`.
* `a...*` contains all elements that are greater than or equal to `a`.
* `a...b` or `a...<b` contains all elements that are greater than or
equal to `a` and less than `b`.
* `a...=b` contains all elements that are greater than or equal to `a`
and less than or equal to `b`.
* `a<...*` contains all elements that are greater than `a`.
* `a<...b` or `a<...<b` contains all elements that are greater than `a`
and less than `b`.
* `a<...=b` contains all elements that are greater than `a` and less
than or equal to `b`.
Benchmarks have shown that importing the iterator-backed parts of the
polymorphic slice library in `Init` impacts build performance. This PR
avoids this problem by separating those parts of the library that do not
rely on iterators from those those that do. Whereever the new slice
notation is used, only the iterator-independent files are imported.
This PR provides an iterator combinator that lifts the emitted values
into a higher universe level via `ULift`. This combinator is then used
to make the subarray iterators universe-polymorphic. Previously, they
were only available for `Subarray α` if `α : Type`.
This PR introduces polymorphic slices in their most basic form. They
come with a notation similar to the new range notation. `Subarray` is
now also a slice and can produce an iterator now. It is intended to
migrate more operations of `Subarray` to the `Slice` wrapper type to
make them available for slices of other types, too.
The PR also moves the `filterMap` combinators into `Init` because they
are used internally to implement iterators on array slices.
