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GHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27

Moduleselective-0.7.0.1Haskell2010

Control.Selective.Rigid.Freer

This is a library for selective applicative functors, or just selective functors for short, an abstraction between applicative functors and monads, introduced in this paper: https://dl.acm.org/doi/10.1145/3341694.

This module defines freer rigid selective functors. Rigid selective functors are those that satisfy the property <*> = apS. Compared to the "free" construction from Control.Selective.Rigid.Free, this "freer" construction does not require the underlying base data type to be a functor.

  • 1 type
  • 6 values

Free rigid selective functors

2 declarations
valueliftSelect :: f a -> Select f a
#

Lift a functor into a free selective computation.

Static analysis

5 declarations
valuegetPure :: Select f a -> Maybe a
#

Extract the resulting value if there are no necessary effects.

valuegetEffects :: Functor f => Select f a -> [f ()]
#

Collect all possible effects in the order they appear in a free selective computation.

valuegetNecessaryEffect :: Functor f => Select f a -> Maybe (f ())
#

Extract the necessary effect from a free selective computation. Note: there can be at most one effect that is statically guaranteed to be necessary.

valuerunSelect :: Selective g => (forall x. f x -> g x) -> Select f a -> g a
#

Given a natural transformation from f to g, this gives a canonical natural transformation from Select f to g.

valuefoldSelect :: Monoid m => (forall x. f x -> m) -> Select f a -> m
#

Concatenate all effects of a free selective computation.