Icelandjack

[PDF] Functional Pearl: Ode on a Random Urn

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This isn't an issue, just a heads up: The paper [*Functional Pearl: Ode on a Random Urn*](http://www.cis.upenn.edu/~llamp/pdf/urns.pdf) proposes a new interface to `frequency`, where it takes an **Urn** data structure...

suchThatNot / suchThatMaybeNot

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Functions that I've found useful, the first one anyway ```haskell suchThatNot :: Gen a -> (a -> Bool) -> Gen a suchThatNot gen f = suchThat gen (not . f)...

Show instance for ‘Gen _’?

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I feel compelled to create this issue, this is as useful as it is not great ```haskell instance Show a => Show (Gen a) where show :: Gen a ->...

Opportunity for Cont/Codensity

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Just brainstorming, nesting [`forAll`](https://hackage.haskell.org/package/QuickCheck-2.9.2/docs/Test-QuickCheck.html#v:forAll), [`shrinking`](https://hackage.haskell.org/package/QuickCheck-2.9.2/docs/Test-QuickCheck.html#v:shrinking) isn't very pretty and they return a continuation (and the type of [`sized`](https://hackage.haskell.org/package/QuickCheck-2.9.2/docs/Test-QuickCheck.html#v:sized) is a [`Codensity`](https://hackage.haskell.org/package/kan-extensions-5.0.1/docs/Control-Monad-Codensity.html#t:Codensity) of `Gen`) ```haskell forAll @_ @Property :: Show a...

‘apply’ and ‘Fn’ for different arities

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The following are used in [containers](https://github.com/haskell/containers/blob/da8c312494a122943315ad48159d2ee034284fde/tests/intmap-strictness.hs#L17) ``` haskell apply2 :: Fun (a, b) c -> a -> b -> c apply2 f a b = apply f (a, b) apply3...

Isomorphism `f (Rep r)` and `r ~> f`

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There is an isomorphism between `f (Rep r)` and natural transformations `r ~> f`: ```haskell one :: RepresentableOf rep r => Functor f => f rep -> r ~> f...

Functor (Foldable..) instances to Bifunctors (Bifoldable..) like Product

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For the change of adding a superclass to `Bifunctor`, and later to `Bifoldable` and `Bitraversable` * https://github.com/haskell/core-libraries-committee/issues/91 * https://github.com/haskell/core-libraries-committee/issues/93 we need `Functor` instances of `Data.Bifunctor.Product` and others. I tried it...

Add predicate to substitute functions

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```haskell substitute :: Monad f => Eq a => a -> f a -> f a -> f a substitute = substituteOf . (==) substituteBy :: Monad m => (a...

Added SOP.Generically and a SOP.Generic instance for GHC.Generically. Updated documentation.

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For #153, this adds: * [*generically* (package)](https://hackage.haskell.org/package/generically) as a dependency, to support versions before `GHC.Generically` was added (base 4.17). * An `SOP.Generic (GHC.Generically a)` instance. ```haskell instance (GHC.Generic a, GFrom...

Missing Generically instance

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Can you add an instance for [`Generically`](https://hackage.haskell.org/package/base-4.17.0.0/docs/GHC-Generics.html#t:Generically) (base 4.17)? Older versions are supported with the [*generically* package](https://hackage.haskell.org/package/generically-0.1/docs/GHC-Generics-Generically.html#t:Generically): ```haskell import GHC.Generics.Generically instance (Generic a, GFlatEncode (Rep a), GFlatDecode (Rep a), GFlatSize...