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Add groupBy for vectors - #427

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alexkalderimis:ajk-vector-group-by
Jan 11, 2022
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Add groupBy for vectors#427
Shimuuar merged 1 commit into
haskell:masterfrom
alexkalderimis:ajk-vector-group-by

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@alexkalderimis

@alexkalderimisalexkalderimis commented Jan 7, 2022

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This adds groupBy for generic vectors, returning a list of
subvectors.

This is similar to #143, aiming to resolve#192

Some of the comments on #143 have been applied here.

Input on testing would be welcome

@Shimuuar

Shimuuar commented Jan 7, 2022

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Looks reasonable to me. Could you add specialized version to Data.Vector, etc and add some haddocks?

@alexkalderimis

alexkalderimis commented Jan 7, 2022

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Thanks for taking a look @Shimuuar - I'll ping you once this has been updated.

konsumlamm
konsumlamm reviewed Jan 10, 2022
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Comment threadvector/src/Data/Vector.hs Outdated
Comment threadvector/src/Data/Vector.hs Outdated
Comment threadvector/src/Data/Vector.hs Outdated
Comment threadvector/src/Data/Vector/Generic.hs Outdated
Comment threadvector/src/Data/Vector/Generic.hs Outdated
Comment threadvector/src/Data/Vector/Generic.hs Outdated
Comment threadvector/src/Data/Vector/Primitive.hs Outdated
Comment threadvector/src/Data/Vector/Storable.hs Outdated
Comment threadvector/src/Data/Vector/Unboxed.hs Outdated
@alexkalderimis

alexkalderimis commented Jan 10, 2022

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Thanks for the suggestions @konsumlamm - please review the updated haddocks, which include some changes to fix failing doctests

@alexkalderimis

alexkalderimis commented Jan 10, 2022

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@Shimuuar - the haddocks and specialized versions should be ready for your review now

@Shimuuar

Shimuuar commented Jan 10, 2022

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Thank you! PR look great.

Doctests fails because of extra whitespace. And could also mentiaion that function does not fuse, and resulting vectors are slices of original vector

@alexkalderimis

alexkalderimis commented Jan 10, 2022

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Thank you! PR look great.

Thanks

Doctests fails because of extra whitespace.

D'oh - easy fix at least

And could also mentiaion that function does not fuse

Can do - thought this was not necessary since the result of the function is a list, not a Vector

and resulting vectors are slices of original vector

The haddocks say: "Split a vector into a list of slices." - is this enough?

@alexkalderimis

alexkalderimis commented Jan 10, 2022

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Back to you, @Shimuuar

@Shimuuar

Shimuuar commented Jan 11, 2022

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Still one test failure. (It's really annoying that doctests only work on 8.6 & 8.8) otherwise good to go. Also could you add changelog entry while you at it

Alex Kalderimis
Add groupBy and group for vectors
410d886
This adds `groupBy` and `group` for generic vectors, returning a list of
slices of the input vector.
Specialized versions of groupBy and group are added for:
- Data.Vector
- Data.Vector.Unboxed
- Data.Vector.Storable
- Data.Vector.Primitive
These functions are all `O(n)`, and do not fuse, but because they
return slices of the input, they do not copy.
@alexkalderimis

alexkalderimis commented Jan 11, 2022

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Still one test failure. (It's really annoying that doctests only work on 8.6 & 8.8) otherwise good to go. Also could you add changelog entry while you at it

It is a little annoying, especially since when I use 8.8.4 locally and run the test suite, I get errors like:

src/Data/Vector.hs:978: failure in expression `import qualified Data.Vector as V'
expected: but got: ^
<no location info>: error:
Could not find module ‘Data.Vector’
Perhaps you meant Data.Functor (from base-4.13.0.0)

Tips on reproducing doctests locally would certainly, be appreciated, but I notice that the checks are running now on push so that is not a big deal.

It looks like I have fixed the remaining issues, so I have added the changelog entry, and squashed the commits for a cleaner history. Back to you @Shimuuar

@Shimuuar

Shimuuar commented Jan 11, 2022

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To run doctests one need not very secret incantation:

vector/.github/workflows/ci.yml

Line 86 in dae9d17

cabal build all --write-ghc-environment-files=always

I still hope we'll get doctests which just works and don't combust spontaneously.

Thank you, it's been a pleasure. Also thank you @konsumlamm for proofreading haddocks

@Shimuuar
Shimuuar merged commit 3883438 into haskell:masterJan 11, 2022
@ShimuuarShimuuar mentioned this pull request Jan 11, 2022
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netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Aug 19, 2022
@0-wiz-0
hs-vector: update to 0.13.0.0.
0986fd5
# Changes in version 0.13.0.0
* `mkType` from `Data.Vector.Generic` is deprecated in favor of
`Data.Data.mkNoRepType`
* The role signatures on several `Vector` types were too permissive, so they
have been tightened up:
* The role signature for `Data.Vector.Mutable.MVector` is now
`type role MVector nominal representational` (previously, both arguments
were `phantom`). [#224](haskell/vector#224)
* The role signature for `Data.Vector.Primitive.Vector` is now
`type role Vector nominal` (previously, it was `phantom`).
The role signature for `Data.Vector.Primitive.Mutable.MVector` is now
`type role MVector nominal nominal` (previously, both arguments were
`phantom`). [#316](haskell/vector#316)
* The role signature for `Data.Vector.Storable.Vector` is now
`type role Vector nominal` (previous, it was `phantom`), and the signature
for `Data.Vector.Storable.Mutable.MVector` is now
`type role MVector nominal nominal` (previous, both arguments were
`phantom`). [#235](haskell/vector#235)
We pick `nominal` for the role of the last argument instead of
`representational` since the internal structure of a `Storable` vector is
determined by the `Storable` instance of the element type, and it is not
guaranteed that the `Storable` instances between two representationally
equal types will preserve this internal structure. One consequence of this
choice is that it is no longer possible to `coerce` between
`Storable.Vector a` and `Storable.Vector b` if `a` and `b` are nominally
distinct but representationally equal types. We now provide
`unsafeCoerce{M}Vector` and `unsafeCast` functions to allow this (the onus
is on the user to ensure that no `Storable` invariants are broken when
using these functions).
* Methods of type classes `Data.Vector.Generic.Mutable.MVector` and
`Data.Vector.Generic.Vector` use concrete monads (`ST`, etc) istead of being
polymorphic (`PrimMonad`, etc). [#335](haskell/vector#335).
This makes it possible to derive `Unbox` with:
* `GeneralizedNewtypeDeriving`
* via `UnboxViaPrim` and `Prim` instance
* via `As` and `IsoUnbox` instance: [#378](haskell/vector#378)
* Add `MonadFix` instance for boxed vectors: [#312](haskell/vector#312)
* Re-export `PrimMonad` and `RealWorld` from mutable vectors:
[#320](haskell/vector#320)
* Add `maximumOn` and `minimumOn`: [#356](haskell/vector#356)
* The functions `scanl1`, `scanl1'`, `scanr1`, and `scanr1'` for immutable
vectors are now defined when given empty vectors as arguments,
in which case they return empty vectors. This new behavior is consistent
with the one of the corresponding functions in `Data.List`.
Prior to this change, applying an empty vector to any of those functions
resulted in an error. This change was introduced in:
[#382](haskell/vector#382)
* Change allocation strategy for `unfoldrN`: [#387](haskell/vector#387)
* Remove `CPP` driven error reporting in favor of `HasCallStack`:
[#397](haskell/vector#397)
* Remove redundant `Storable` constraints on to/from `ForeignPtr` conversions:
[#394](haskell/vector#394)
* Add `unsafeCast` to `Primitive` vectors: [#401](haskell/vector#401)
* Make `(!?)` operator strict: [#402](haskell/vector#402)
* Add `readMaybe`: [#425](haskell/vector#425)
* Add `groupBy` and `group` for `Data.Vector.Generic` and the specialized
version in `Data.Vector`, `Data.Vector.Unboxed`, `Data.Vector.Storable` and
`Data.Vector.Primitive`. [#427](haskell/vector#427)
* Add `toArraySlice` and `unsafeFromArraySlice` functions for conversion to and
from the underlying boxed `Array`: [#434](haskell/vector#434)
msk pushed a commit to msk/pkgsrc that referenced this pull request May 11, 2026
@0-wiz-0
hs-vector: update to 0.13.0.0.
b6bb83d
# Changes in version 0.13.0.0
* `mkType` from `Data.Vector.Generic` is deprecated in favor of
`Data.Data.mkNoRepType`
* The role signatures on several `Vector` types were too permissive, so they
have been tightened up:
* The role signature for `Data.Vector.Mutable.MVector` is now
`type role MVector nominal representational` (previously, both arguments
were `phantom`). [#224](haskell/vector#224)
* The role signature for `Data.Vector.Primitive.Vector` is now
`type role Vector nominal` (previously, it was `phantom`).
The role signature for `Data.Vector.Primitive.Mutable.MVector` is now
`type role MVector nominal nominal` (previously, both arguments were
`phantom`). [#316](haskell/vector#316)
* The role signature for `Data.Vector.Storable.Vector` is now
`type role Vector nominal` (previous, it was `phantom`), and the signature
for `Data.Vector.Storable.Mutable.MVector` is now
`type role MVector nominal nominal` (previous, both arguments were
`phantom`). [#235](haskell/vector#235)
We pick `nominal` for the role of the last argument instead of
`representational` since the internal structure of a `Storable` vector is
determined by the `Storable` instance of the element type, and it is not
guaranteed that the `Storable` instances between two representationally
equal types will preserve this internal structure. One consequence of this
choice is that it is no longer possible to `coerce` between
`Storable.Vector a` and `Storable.Vector b` if `a` and `b` are nominally
distinct but representationally equal types. We now provide
`unsafeCoerce{M}Vector` and `unsafeCast` functions to allow this (the onus
is on the user to ensure that no `Storable` invariants are broken when
using these functions).
* Methods of type classes `Data.Vector.Generic.Mutable.MVector` and
`Data.Vector.Generic.Vector` use concrete monads (`ST`, etc) istead of being
polymorphic (`PrimMonad`, etc). [#335](haskell/vector#335).
This makes it possible to derive `Unbox` with:
* `GeneralizedNewtypeDeriving`
* via `UnboxViaPrim` and `Prim` instance
* via `As` and `IsoUnbox` instance: [#378](haskell/vector#378)
* Add `MonadFix` instance for boxed vectors: [#312](haskell/vector#312)
* Re-export `PrimMonad` and `RealWorld` from mutable vectors:
[#320](haskell/vector#320)
* Add `maximumOn` and `minimumOn`: [#356](haskell/vector#356)
* The functions `scanl1`, `scanl1'`, `scanr1`, and `scanr1'` for immutable
vectors are now defined when given empty vectors as arguments,
in which case they return empty vectors. This new behavior is consistent
with the one of the corresponding functions in `Data.List`.
Prior to this change, applying an empty vector to any of those functions
resulted in an error. This change was introduced in:
[#382](haskell/vector#382)
* Change allocation strategy for `unfoldrN`: [#387](haskell/vector#387)
* Remove `CPP` driven error reporting in favor of `HasCallStack`:
[#397](haskell/vector#397)
* Remove redundant `Storable` constraints on to/from `ForeignPtr` conversions:
[#394](haskell/vector#394)
* Add `unsafeCast` to `Primitive` vectors: [#401](haskell/vector#401)
* Make `(!?)` operator strict: [#402](haskell/vector#402)
* Add `readMaybe`: [#425](haskell/vector#425)
* Add `groupBy` and `group` for `Data.Vector.Generic` and the specialized
version in `Data.Vector`, `Data.Vector.Unboxed`, `Data.Vector.Storable` and
`Data.Vector.Primitive`. [#427](haskell/vector#427)
* Add `toArraySlice` and `unsafeFromArraySlice` functions for conversion to and
from the underlying boxed `Array`: [#434](haskell/vector#434)
jperkin pushed a commit to TritonDataCenter/pkgsrc that referenced this pull request May 14, 2026
@0-wiz-0
hs-vector: update to 0.13.0.0.
1740af9
# Changes in version 0.13.0.0
* `mkType` from `Data.Vector.Generic` is deprecated in favor of
`Data.Data.mkNoRepType`
* The role signatures on several `Vector` types were too permissive, so they
have been tightened up:
* The role signature for `Data.Vector.Mutable.MVector` is now
`type role MVector nominal representational` (previously, both arguments
were `phantom`). [#224](haskell/vector#224)
* The role signature for `Data.Vector.Primitive.Vector` is now
`type role Vector nominal` (previously, it was `phantom`).
The role signature for `Data.Vector.Primitive.Mutable.MVector` is now
`type role MVector nominal nominal` (previously, both arguments were
`phantom`). [#316](haskell/vector#316)
* The role signature for `Data.Vector.Storable.Vector` is now
`type role Vector nominal` (previous, it was `phantom`), and the signature
for `Data.Vector.Storable.Mutable.MVector` is now
`type role MVector nominal nominal` (previous, both arguments were
`phantom`). [#235](haskell/vector#235)
We pick `nominal` for the role of the last argument instead of
`representational` since the internal structure of a `Storable` vector is
determined by the `Storable` instance of the element type, and it is not
guaranteed that the `Storable` instances between two representationally
equal types will preserve this internal structure. One consequence of this
choice is that it is no longer possible to `coerce` between
`Storable.Vector a` and `Storable.Vector b` if `a` and `b` are nominally
distinct but representationally equal types. We now provide
`unsafeCoerce{M}Vector` and `unsafeCast` functions to allow this (the onus
is on the user to ensure that no `Storable` invariants are broken when
using these functions).
* Methods of type classes `Data.Vector.Generic.Mutable.MVector` and
`Data.Vector.Generic.Vector` use concrete monads (`ST`, etc) istead of being
polymorphic (`PrimMonad`, etc). [#335](haskell/vector#335).
This makes it possible to derive `Unbox` with:
* `GeneralizedNewtypeDeriving`
* via `UnboxViaPrim` and `Prim` instance
* via `As` and `IsoUnbox` instance: [#378](haskell/vector#378)
* Add `MonadFix` instance for boxed vectors: [#312](haskell/vector#312)
* Re-export `PrimMonad` and `RealWorld` from mutable vectors:
[#320](haskell/vector#320)
* Add `maximumOn` and `minimumOn`: [#356](haskell/vector#356)
* The functions `scanl1`, `scanl1'`, `scanr1`, and `scanr1'` for immutable
vectors are now defined when given empty vectors as arguments,
in which case they return empty vectors. This new behavior is consistent
with the one of the corresponding functions in `Data.List`.
Prior to this change, applying an empty vector to any of those functions
resulted in an error. This change was introduced in:
[#382](haskell/vector#382)
* Change allocation strategy for `unfoldrN`: [#387](haskell/vector#387)
* Remove `CPP` driven error reporting in favor of `HasCallStack`:
[#397](haskell/vector#397)
* Remove redundant `Storable` constraints on to/from `ForeignPtr` conversions:
[#394](haskell/vector#394)
* Add `unsafeCast` to `Primitive` vectors: [#401](haskell/vector#401)
* Make `(!?)` operator strict: [#402](haskell/vector#402)
* Add `readMaybe`: [#425](haskell/vector#425)
* Add `groupBy` and `group` for `Data.Vector.Generic` and the specialized
version in `Data.Vector`, `Data.Vector.Unboxed`, `Data.Vector.Storable` and
`Data.Vector.Primitive`. [#427](haskell/vector#427)
* Add `toArraySlice` and `unsafeFromArraySlice` functions for conversion to and
from the underlying boxed `Array`: [#434](haskell/vector#434)
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group and groupBy

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@alexkalderimis@Shimuuar@konsumlamm