com.jnape.palatable.lambda.monad

Interface Monad<A,M extends Monad<?,M>>

Type Parameters:

A - the type of the parameter

M - the unification parameter to more tightly type-constrain Monads to themselves

All Superinterfaces:

Applicative<A,M>, Functor<A,M>

All Known Subinterfaces:

BiMonoidFactory<A,B,C>, BiPredicate<A,B>, BiSemigroupFactory<A,B,C>, Effect<A>, Fn0<A>, Fn1<A,B>, Fn2<A,B,C>, Fn3<A,B,C,D>, Fn4<A,B,C,D,E>, Fn5<A,B,C,D,E,F>, Fn6<A,B,C,D,E,F,G>, Fn7<A,B,C,D,E,F,G,H>, Fn8<A,B,C,D,E,F,G,H,I>, Iso<S,T,A,B>, Iso.Simple<S,A>, Kleisli<A,B,M,MB>, Lens<S,T,A,B>, Lens.Simple<S,A>, MonadError<E,A,M>, MonadReader<R,A,MR>, MonadRec<A,M>, MonadT<M,A,MT,T>, MonadWriter<W,A,MW>, Monoid<A>, MonoidFactory<A,B>, Predicate<A>, Prism<S,T,A,B>, Prism.Simple<S,A>, Schema<Values>, Semigroup<A>, SemigroupFactory<A,B>, TypeSafeKey<A,B>, TypeSafeKey.Simple<A>

All Known Implementing Classes:

Absent, AddAll, All, Alter, And, Any, AutoBracket, Between, Both, Bracket, CartesianProduct, CatMaybes, Choice2, Choice3, Choice4, Choice5, Choice6, Choice7, Choice8, Clamp, CmpEq, CmpEqBy, Coalesce, Collapse, Collapse, Compose, Compose, Concat, Cons, Const, Constantly, Cycle, Difference, Distinct, Downcast, Drop, DropWhile, Either, EitherT, Empty, Endo, EndoK, Eq, Filter, Find, First, Flatten, FoldLeft, FoldRight, Force, GroupBy, GT, GTBy, GTE, GTEBy, Head, Id, Identity, IdentityT, IfThenElse, InGroupsOf, Init, Inits, Intersection, Intersperse, Into, Into1, Into3, Into4, Into5, Into6, Into7, Into8, IO, Iterate, Join, LambdaIterable, Last, Last, Lazy, LazyRec, LazyT, LeftAll, LeftAll, LeftAny, LeftAny, LiftA2, LiftA3, LiftA4, LiftA5, LiftA6, LiftA7, LT, LTBy, LTE, LTEBy, Magnetize, MagnetizeBy, Map, Market, Matching, Max, MaxBy, Maybe, MaybeT, Merge, Merge, MergeMaps, Min, MinBy, Not, Occurrences, Or, Over, Partition, Peek, Peek2, Pre, PrependAll, Present, PutAll, RateLimit, Re, ReaderT, RecursiveResult, ReduceLeft, ReduceRight, Repeat, Replicate, Reverse, RightAll, RightAll, RightAny, RightAny, RunAll, RunAll, SafeT, ScanLeft, Sequence, Set, SingletonHList, Size, Slide, Snoc, Sort, SortBy, SortWith, Span, State, StateT, Tagged, Tail, Tails, Take, TakeWhile, These, Times, ToArray, ToCollection, ToMap, Trampoline, Trivial, Try, Tuple2, Tuple3, Tuple4, Tuple5, Tuple6, Tuple7, Tuple8, Tupler2, Uncons, Under, Unfoldr, Union, Until, Upcast, View, Writer, WriterT, Xor, Zip, ZipWith

public interface Monad<A,M extends Monad<?,M>>
extends Applicative<A,M>

Monads are Applicative functors that support a flattening operation to unwrap M<M<A>> -> M<A>. This flattening operation, coupled with Applicative.zip(Applicative), gives rise to flatMap(Fn1), a binding operation that maps the carrier value to a new monad instance in the same category, and then unwraps the outer layer.

In addition to the applicative laws, there are 3 specific monad laws that monads should obey:

• left identity: m.pure(a).flatMap(fn).equals(fn.apply(a))
• right identity: m.flatMap(m::pure).equals(m)
• associativity: m.flatMap(f).flatMap(g).equals(m.flatMap(a -> f.apply(a).flatMap(g)))

For more information, read about Monads.

Method Summary

Modifier and Type	Method and Description
default <B> Monad<B,M>	discardL(Applicative<B,M> appB) Sequence both this Applicative and appB, discarding this Applicative's result and returning appB.
default <B> Monad<A,M>	discardR(Applicative<B,M> appB) Sequence both this Applicative and appB, discarding appB's result and returning this Applicative.
<B> Monad<B,M>	flatMap(Fn1<? super A,? extends Monad<B,M>> f) Chain dependent computations that may continue or short-circuit based on previous results.
default <B> Monad<B,M>	fmap(Fn1<? super A,? extends B> fn) Covariantly transmute this functor's parameter using the given mapping function.
static <M extends Monad<?,M>,A,MA extends Monad<A,M>> MA	join(Monad<? extends MA,M> mma) Convenience static method equivalent to flatMap(id());
default <B> Lazy<? extends Monad<B,M>>	lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,M>> lazyAppFn) Given a lazy instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports.
<B> Monad<B,M>	pure(B b) Lift the value b into this applicative functor.
default <B> Monad<B,M>	zip(Applicative<Fn1<? super A,? extends B>,M> appFn) Given another instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports.

Methods inherited from interface com.jnape.palatable.lambda.functor.Functor

coerce

Method Detail

flatMap

<B> Monad<B,M> flatMap(Fn1<? super A,? extends Monad<B,M>> f)

Chain dependent computations that may continue or short-circuit based on previous results.

Type Parameters:

B - the resulting monad parameter type

Parameters:

f - the dependent computation over A

Returns:

the new monad instance

pure

<B> Monad<B,M> pure(B b)

Lift the value b into this applicative functor.

Specified by:

pure in interface Applicative<A,M extends Monad<?,M>>

Type Parameters:

B - the type of the returned applicative's parameter

Parameters:

b - the value

Returns:

an instance of this applicative over b

fmap

default <B> Monad<B,M> fmap(Fn1<? super A,? extends B> fn)

Covariantly transmute this functor's parameter using the given mapping function. Generally this method is specialized to return an instance of the class implementing Functor.

Specified by:

fmap in interface Applicative<A,M extends Monad<?,M>>

Specified by:

fmap in interface Functor<A,M extends Monad<?,M>>

Type Parameters:

B - the new parameter type

Parameters:

fn - the mapping function

Returns:

a functor over B (the new parameter type)

zip

default <B> Monad<B,M> zip(Applicative<Fn1<? super A,? extends B>,M> appFn)

Given another instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports.

Specified by:

zip in interface Applicative<A,M extends Monad<?,M>>

Type Parameters:

B - the resulting applicative parameter type

Parameters:

appFn - the other applicative instance

Returns:

the mapped applicative

lazyZip

default <B> Lazy<? extends Monad<B,M>> lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,M>> lazyAppFn)

Given a lazy instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports. This is useful for applicatives that support lazy evaluation and early termination.

Specified by:

lazyZip in interface Applicative<A,M extends Monad<?,M>>

Type Parameters:

B - the resulting applicative parameter type

Parameters:

lazyAppFn - the lazy other applicative instance

Returns:

the mapped applicative

See Also:

Maybe, Either

discardL

default <B> Monad<B,M> discardL(Applicative<B,M> appB)

Sequence both this Applicative and appB, discarding this Applicative's result and returning appB. This is generally useful for sequentially performing side-effects.

Specified by:

discardL in interface Applicative<A,M extends Monad<?,M>>

Type Parameters:

B - the type of the returned Applicative's parameter

Parameters:

appB - the other Applicative

Returns:

appB

discardR

default <B> Monad<A,M> discardR(Applicative<B,M> appB)

Sequence both this Applicative and appB, discarding appB's result and returning this Applicative. This is generally useful for sequentially performing side-effects.

Specified by:

discardR in interface Applicative<A,M extends Monad<?,M>>

Type Parameters:

B - the type of appB's parameter

Parameters:

appB - the other Applicative

Returns:

this Applicative

join

static <M extends Monad<?,M>,A,MA extends Monad<A,M>> MA join(Monad<? extends MA,M> mma)

Convenience static method equivalent to flatMap(id());

Type Parameters:

M - the monad type

A - the nested type parameter

MA - the nested monad

Parameters:

mma - the outer monad

Returns:

the nested monad