Local
@implicitNotFound("Could not find an implicit instance of Local[${F}, ${E}]. If you have a\nvalue of type ${E} in scope, or a way of computing one, you may want to construct\na value of type Kleisli for this call-site, rather than type ${F}. An example type:\n\n Kleisli[${F}, ${E}, *]\n\nIf you do not have an ${E} or a way of getting one, you should add\nan implicit parameter of this type to your function. For example:\n\n (implicit flocal: Local[${F}, ${E}])\n") trait Local[F <: ([_$1] =>> Any), E] extends Ask[F, E] with Serializable
Local[F, E] lets you alter the E value that is observed by an F[A] valueusing
ask; the modification can only be observed from within that F[A] value.Local[F, E] has three external laws:{{{
def askReflectsLocal(f: E => E) = {
local(f)(ask) <-> ask map f
}
def localPureIsPure[A]
(a: A, f: E => E) = {
local(f)(pure(a)) <-> pure(a)
}
local(f)(pure(a)) <-> pure(a)
}
def localDistributesOverAp[A, B]
(fa: F[A]
, ff: F[A => B]
, f: E => E) = {
local(f)(ff ap fa) <-> local(f)(ff) ap local(f)(fa)
}
}}}
local(f)(ff ap fa) <-> local(f)(ff) ap local(f)(fa)
}
}}}
Local has one internal law:{{{
def scopeIsLocalConst(fa: F[A] , e: E) = {
scope(e)(fa) <-> local(_ => e)(fa)
}
}}}
- Companion
- object