Control.Apply
#Apply
class Apply :: (Type -> Type) -> Constraint
class (Functor f) <= Apply f where
The Apply
class provides the (<*>)
which is used to apply a function
to an argument under a type constructor.
Apply
can be used to lift functions of two or more arguments to work on
values wrapped with the type constructor f
. It might also be understood
in terms of the lift2
function:
lift2 :: forall f a b c. Apply f => (a -> b -> c) -> f a -> f b -> f c
lift2 f a b = f <$> a <*> b
(<*>)
is recovered from lift2
as lift2 ($)
. That is, (<*>)
lifts
the function application operator ($)
to arguments wrapped with the
type constructor f
.
Put differently...
foo =
functionTakingNArguments <$> computationProducingArg1
<*> computationProducingArg2
<*> ...
<*> computationProducingArgN
Instances must satisfy the following law in addition to the Functor
laws:
- Associative composition:
(<<<) <$> f <*> g <*> h = f <*> (g <*> h)
Formally, Apply
represents a strong lax semi-monoidal endofunctor.
Members
apply :: forall a b. f (a -> b) -> f a -> f b
Instances
#(<*>)
Operator alias for Control.Apply.apply (left-associative / precedence 4)
#applyFirst
applyFirst :: forall a b f. Apply f => f a -> f b -> f a
Combine two effectful actions, keeping only the result of the first.
#(<*)
Operator alias for Control.Apply.applyFirst (left-associative / precedence 4)
#applySecond
applySecond :: forall a b f. Apply f => f a -> f b -> f b
Combine two effectful actions, keeping only the result of the second.
#(*>)
Operator alias for Control.Apply.applySecond (left-associative / precedence 4)
#lift2
#lift3
#lift4
#lift5
Re-exports from Data.Functor
#Functor
class Functor :: (Type -> Type) -> Constraint
class Functor f where
A Functor
is a type constructor which supports a mapping operation
map
.
map
can be used to turn functions a -> b
into functions
f a -> f b
whose argument and return types use the type constructor f
to represent some computational context.
Instances must satisfy the following laws:
- Identity:
map identity = identity
- Composition:
map (f <<< g) = map f <<< map g
Members
map :: forall a b. (a -> b) -> f a -> f b
Instances
#void
void :: forall f a. Functor f => f a -> f Unit
The void
function is used to ignore the type wrapped by a
Functor
, replacing it with Unit
and keeping only the type
information provided by the type constructor itself.
void
is often useful when using do
notation to change the return type
of a monadic computation:
main = forE 1 10 \n -> void do
print n
print (n * n)
#(<$>)
Operator alias for Data.Functor.map (left-associative / precedence 4)
#(<$)
Operator alias for Data.Functor.voidRight (left-associative / precedence 4)
#(<#>)
Operator alias for Data.Functor.mapFlipped (left-associative / precedence 1)
#($>)
Operator alias for Data.Functor.voidLeft (left-associative / precedence 4)
Packages
assert
catenable-lists
const
convertable-options
datetime-parsing
debug
distributive
erl-atom
erl-gun
erl-lager
erl-logger
erl-maps
erl-modules
erl-nativerefs
erl-opentelemetry
- OpenTelemetry.Metrics
- OpenTelemetry.Metrics.Counter
- OpenTelemetry.Metrics.Meter
- OpenTelemetry.Metrics.SumObserver
- OpenTelemetry.Metrics.UpDownCounter
- OpenTelemetry.Metrics.UpDownSumObserver
- OpenTelemetry.Metrics.ValueObserver
- OpenTelemetry.Metrics.ValueRecorder
- OpenTelemetry.Tracing
- OpenTelemetry.Tracing.Baggage
- OpenTelemetry.Tracing.Ctx
- OpenTelemetry.Tracing.Propagator.TextMap
- OpenTelemetry.Tracing.Span
- OpenTelemetry.Tracing.Tracer
- Tracing.Attributes
erl-process
erl-queue
erl-ranch
erl-simplebus
erl-ssl
erl-test-eunit
erl-test-eunit-discovery
erl-tuples
erl-untagged-union
exceptions
exists
expect-inferred
functions
graphs
heterogeneous
identity
integers
invariant
js-uri
lazy
lcg
math
media-types
newtype
nonempty
nullable
ordered-collections
partial
prelude
- Control.Applicative
- Control.Apply
- Control.Bind
- Control.Category
- Control.Monad
- Control.Semigroupoid
- Data.Boolean
- Data.BooleanAlgebra
- Data.Bounded
- Data.Bounded.Generic
- Data.CommutativeRing
- Data.DivisionRing
- Data.Eq
- Data.Eq.Generic
- Data.EuclideanRing
- Data.Field
- Data.Function
- Data.Functor
- Data.Generic.Rep
- Data.HeytingAlgebra
- Data.HeytingAlgebra.Generic
- Data.Monoid
- Data.Monoid.Additive
- Data.Monoid.Conj
- Data.Monoid.Disj
- Data.Monoid.Dual
- Data.Monoid.Endo
- Data.Monoid.Generic
- Data.Monoid.Multiplicative
- Data.NaturalTransformation
- Data.Ord
- Data.Ord.Generic
- Data.Ordering
- Data.Ring
- Data.Ring.Generic
- Data.Semigroup
- Data.Semigroup.First
- Data.Semigroup.Generic
- Data.Semigroup.Last
- Data.Semiring
- Data.Semiring.Generic
- Data.Show
- Data.Show.Generic
- Data.Symbol
- Data.Unit
- Data.Void
- Record.Unsafe
- Type.Data.Row
- Type.Data.RowList
- Type.Proxy
profunctor-lenses
- Data.Lens.AffineTraversal
- Data.Lens.At
- Data.Lens.Common
- Data.Lens.Fold
- Data.Lens.Fold.Partial
- Data.Lens.Getter
- Data.Lens.Grate
- Data.Lens.Index
- Data.Lens.Indexed
- Data.Lens.Internal.Bazaar
- Data.Lens.Internal.Exchange
- Data.Lens.Internal.Focusing
- Data.Lens.Internal.Forget
- Data.Lens.Internal.Grating
- Data.Lens.Internal.Indexed
- Data.Lens.Internal.Market
- Data.Lens.Internal.Re
- Data.Lens.Internal.Shop
- Data.Lens.Internal.Stall
- Data.Lens.Internal.Tagged
- Data.Lens.Internal.Wander
- Data.Lens.Internal.Zipping
- Data.Lens.Iso
- Data.Lens.Iso.Newtype
- Data.Lens.Lens
- Data.Lens.Lens.Product
- Data.Lens.Lens.Tuple
- Data.Lens.Lens.Unit
- Data.Lens.Lens.Void
- Data.Lens.Prism
- Data.Lens.Prism.Coproduct
- Data.Lens.Prism.Either
- Data.Lens.Prism.Maybe
- Data.Lens.Record
- Data.Lens.Setter
- Data.Lens.Traversal
- Data.Lens.Types
- Data.Lens.Zoom
psci-support
quickcheck-laws
- Test.QuickCheck.Laws
- Test.QuickCheck.Laws.Control.Alt
- Test.QuickCheck.Laws.Control.Alternative
- Test.QuickCheck.Laws.Control.Applicative
- Test.QuickCheck.Laws.Control.Apply
- Test.QuickCheck.Laws.Control.Bind
- Test.QuickCheck.Laws.Control.Category
- Test.QuickCheck.Laws.Control.Comonad
- Test.QuickCheck.Laws.Control.Extend
- Test.QuickCheck.Laws.Control.Monad
- Test.QuickCheck.Laws.Control.MonadPlus
- Test.QuickCheck.Laws.Control.MonadZero
- Test.QuickCheck.Laws.Control.Plus
- Test.QuickCheck.Laws.Control.Semigroupoid
- Test.QuickCheck.Laws.Data.BooleanAlgebra
- Test.QuickCheck.Laws.Data.Bounded
- Test.QuickCheck.Laws.Data.BoundedEnum
- Test.QuickCheck.Laws.Data.CommutativeRing
- Test.QuickCheck.Laws.Data.DivisionRing
- Test.QuickCheck.Laws.Data.Eq
- Test.QuickCheck.Laws.Data.EuclideanRing
- Test.QuickCheck.Laws.Data.Field
- Test.QuickCheck.Laws.Data.Foldable
- Test.QuickCheck.Laws.Data.Functor
- Test.QuickCheck.Laws.Data.FunctorWithIndex
- Test.QuickCheck.Laws.Data.HeytingAlgebra
- Test.QuickCheck.Laws.Data.Monoid
- Test.QuickCheck.Laws.Data.Ord
- Test.QuickCheck.Laws.Data.Ring
- Test.QuickCheck.Laws.Data.Semigroup
- Test.QuickCheck.Laws.Data.Semiring
random
rationals
record-prefix
refs
safe-coerce
semirings
simple-json
strings
- Data.Char
- Data.Char.Gen
- Data.String.CaseInsensitive
- Data.String.CodePoints
- Data.String.CodeUnits
- Data.String.Common
- Data.String.Gen
- Data.String.NonEmpty.CaseInsensitive
- Data.String.NonEmpty.CodePoints
- Data.String.NonEmpty.CodeUnits
- Data.String.NonEmpty.Internal
- Data.String.Pattern
- Data.String.Regex
- Data.String.Regex.Flags
- Data.String.Regex.Unsafe
- Data.String.Unsafe
tailrec
transformers
- Control.Comonad.Env
- Control.Comonad.Env.Class
- Control.Comonad.Env.Trans
- Control.Comonad.Store
- Control.Comonad.Store.Class
- Control.Comonad.Store.Trans
- Control.Comonad.Traced
- Control.Comonad.Traced.Class
- Control.Comonad.Traced.Trans
- Control.Comonad.Trans.Class
- Control.Monad.Cont
- Control.Monad.Cont.Class
- Control.Monad.Cont.Trans
- Control.Monad.Error.Class
- Control.Monad.Except
- Control.Monad.Except.Trans
- Control.Monad.Identity.Trans
- Control.Monad.List.Trans
- Control.Monad.Maybe.Trans
- Control.Monad.RWS
- Control.Monad.RWS.Trans
- Control.Monad.Reader
- Control.Monad.Reader.Class
- Control.Monad.Reader.Trans
- Control.Monad.State
- Control.Monad.State.Class
- Control.Monad.State.Trans
- Control.Monad.Trans.Class
- Control.Monad.Writer
- Control.Monad.Writer.Class
- Control.Monad.Writer.Trans
type-equality
undefinable
unfoldable
unsafe-coerce
unsafe-reference
uri
- URI.AbsoluteURI
- URI.Authority
- URI.Common
- URI.Extra.MultiHostPortPair
- URI.Extra.QueryPairs
- URI.Extra.UserPassInfo
- URI.Fragment
- URI.HierarchicalPart
- URI.Host
- URI.Host.Gen
- URI.Host.IPv4Address
- URI.Host.IPv6Address
- URI.Host.RegName
- URI.HostPortPair
- URI.HostPortPair.Gen
- URI.Path
- URI.Path.Absolute
- URI.Path.NoScheme
- URI.Path.Rootless
- URI.Path.Segment
- URI.Port
- URI.Port.Gen
- URI.Query
- URI.RelativePart
- URI.RelativeRef
- URI.Scheme
- URI.Scheme.Common
- URI.URI
- URI.URIRef
- URI.UserInfo