Copyright	(c) 2019 Composewell Technologies
License	BSD3
Maintainer	streamly@composewell.com
Stability	experimental
Portability	GHC
Safe Haskell	Safe-Inferred
Language	Haskell2010

Streamly.Internal.Data.Fold.Step

Contents

Types

Description

Synopsis

data Step s b
- = Partial !s
- | Done !b
mapMStep :: Applicative m => (a -> m b) -> Step s a -> m (Step s b)
chainStepM :: Applicative m => (s1 -> m s2) -> (a -> m (Step s2 b)) -> Step s1 a -> m (Step s2 b)

Types

data Step s b Source #

Represents the result of the step of a Fold. Partial returns an intermediate state of the fold, the fold step can be called again with the state or the driver can use extract on the state to get the result out. Done returns the final result and the fold cannot be driven further.

Pre-release

Constructors

Partial !s
Done !b

Instances

Instances details

Bifunctor Step Source #	`first` maps over `Partial` and `second` maps over `Done`.
Instance details Defined in Streamly.Internal.Data.Fold.Step Methods bimap :: (a -> b) -> (c -> d) -> Step a c -> Step b d # first :: (a -> b) -> Step a c -> Step b c # second :: (b -> c) -> Step a b -> Step a c #
Functor (Step s) Source #	`fmap` maps over `Done`. fmap = `second`
Instance details Defined in Streamly.Internal.Data.Fold.Step Methods fmap :: (a -> b) -> Step s a -> Step s b # (<$) :: a -> Step s b -> Step s a #

mapMStep :: Applicative m => (a -> m b) -> Step s a -> m (Step s b) Source #

Map a monadic function over the result b in Step s b.

Internal

chainStepM :: Applicative m => (s1 -> m s2) -> (a -> m (Step s2 b)) -> Step s1 a -> m (Step s2 b) Source #

If Partial then map the state, if Done then call the next step.