trait
Applicative[M[_]] extends Functor[M]
Abstract Value Members
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abstract
def
apply[T](v: T): M[T]
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abstract
def
join[T, U](mt: M[T], mu: M[U]): M[(T, U)]
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abstract
def
map[T, U](m: M[T])(fn: (T) ⇒ U): M[U]
Concrete Value Members
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final
def
!=(arg0: AnyRef): Boolean
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final
def
!=(arg0: Any): Boolean
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final
def
##(): Int
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final
def
==(arg0: AnyRef): Boolean
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final
def
==(arg0: Any): Boolean
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final
def
asInstanceOf[T0]: T0
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def
clone(): AnyRef
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final
def
eq(arg0: AnyRef): Boolean
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def
equals(arg0: Any): Boolean
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def
finalize(): Unit
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final
def
getClass(): Class[_]
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def
hashCode(): Int
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final
def
isInstanceOf[T0]: Boolean
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def
join[T1, T2, T3, T4, T5](m1: M[T1], m2: M[T2], m3: M[T3], m4: M[T4], m5: M[T5]): M[(T1, T2, T3, T4, T5)]
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def
join[T1, T2, T3, T4](m1: M[T1], m2: M[T2], m3: M[T3], m4: M[T4]): M[(T1, T2, T3, T4)]
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def
join[T1, T2, T3](m1: M[T1], m2: M[T2], m3: M[T3]): M[(T1, T2, T3)]
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def
joinWith[T, U, V](mt: M[T], mu: M[U])(fn: (T, U) ⇒ V): M[V]
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final
def
ne(arg0: AnyRef): Boolean
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final
def
notify(): Unit
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final
def
notifyAll(): Unit
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def
sequence[T](ms: Seq[M[T]]): M[Seq[T]]
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final
def
synchronized[T0](arg0: ⇒ T0): T0
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def
toString(): String
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final
def
wait(): Unit
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final
def
wait(arg0: Long, arg1: Int): Unit
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final
def
wait(arg0: Long): Unit
Inherited from AnyRef
Inherited from Any
Simple implementation of an Applicative type-class. There are many choices for the canonical second operation (join, sequence, joinWith, ap), all equivalent. For a Functor modeling concurrent computations with failure, like Future, combining results with join can save a lot of time over combining with flatMap. (Given two operations, if the second fails before the first completes, one can fail the entire computation right then. With flatMap, one would have to wait for the first operation to complete before failing it.)
Laws Applicatives must follow: map(apply(x))(f) == apply(f(x)) join(apply(x), apply(y)) == apply((x, y)) (sequence and joinWith specialize join - they should behave appropriately)