Changelog for fusedeffects0.5.0.0
v0.5.0.0

Derives
Generic1
instances for all nonexistentiallyquantified effect datatypes. 
Derives
Foldable
&Traversable
instances for:+:
. 
Defines
MonadFix
instances for all of the carriers. 
Reexports
run
,:+:
, andMember
fromControl.Effect.Carrier
, reducing the number of imports needed when defining new effects. 
Reexports
Carrier
,Member
, andrun
from the various effect modules, reducing the number of imports needed when using existing effects.
Backwardsincompatible changes

Replaces
runResource
with an equivalent function that usesMonadUnliftIO
to select the correct unlifting function (a lawithResource
, which is removed in favor ofrunResource
). 
Changes the signature of
eff
fromsig m (m a) > m a
tosig m a > m a
, requiring effects to holdm k
in their continuation positions instead of merelyk
. This was done in order to improve interoperability with other presentations of higherorder syntax, e.g.bound
; syntax used withbound
can now be givenHFunctor
andCarrier
instances.To upgrade effects used with previous versions, change any continuations from
k
tom k
. If no existential type variables appear in the effect, you can deriveGeneric1
, and thenceHFunctor
&Effect
instances. Otherwise, implement the required instances by hand. Since continuation positions now occur inm
,hmap
definitions will have to apply the higherorder function to these as well. 
Adds
Functor
constraints tohmap
andMonad
constraints tohandle
, allowing a greater variety of instances to be defined (e.g. for recursivelynested syntax). 
Replaces the default definitions of
hmap
andhandle
with derivations based onGeneric1
instead ofCoercible
. Therefore, firstorder effects wishing to derive these instances will requireGeneric1
instances, presumably derived usingXDeriveGeneric
. 
Moves
send
fromControl.Effect.Sum
toControl.Effect.Carrier
. Likewise removes the reexport ofsend
fromControl.Effect
. 
Deprecates
fmap'
in favour offmap
. 
Deprecates
handlePure
in favour ofhmap
.
v0.4.0.0
Backwardsincompatible changes
 Removes APIs deprecated in 0.3.0.0, including
Eff
,interpret
,ret
, and thehandle*
family of helper functions.
Other changes
 Adds the ability to derive default instances of
HFunctor
andEffect
for firstorder effects, using theXDeriveAnyClass
extension.  Adds a generic
Interpose
effect that enables arbitrary "eavesdropping" on other effects.
0.3.1.0
 Improved speed of
Reader
,State
,Writer
, andPure
effects by defining and inlining auxiliaryApplicative
methods.  Adds
runInterpret
&runInterpretState
handlers inControl.Effect.Interpret
as a convenient way to experiment with effect handlers without defining a new carrier type andCarrier
instance. Such handlers are somewhat less efficient than customCarrier
s, but allow for a smooth upgrade path when more efficiency is required.  Added
unliftiocore
as a dependency so as to provide a blessed API for unliftstyle effects and a solution to the cubiccaller problem.
0.3.0.0
Backwardsincompatible changes
 Adds
Monad
as a superclass ofCarrier
, obviating the need for a lot of constraints, andMonad
instances for all carrier types. This is a backwardsincompatible change, as any carriers users have defined now requireMonad
instances. Note that in many cases carriers can be composed out of existing carriers and monad transformers, and thus these instances can often be derived usingXGeneralizedNewtypeDeriving
. We also recommend compiling withWredundantconstraints
as many of these can now be removed.  Replaces
AltC
with a new carrier,NonDetC
, based on Ralf Hinze’s work in Deriving Backtracking Monad Transformers. This is a backwardsincompatible change.AltC
was equivalent to theListT
monad transformer, and had the same wellknown limitation to commutative monads. Therefore, the elimination ofEff
required a more durable approach.  Removes
Branch
. This is a backwardsincompatible change, but was necessitated by the difficulty of implementing correctApplicative
&Monad
instances for carriers which used it. Carriers which were employingBranch
internally should be reimplemented usingNonDetC
or a similar approach; seeCutC
andCullC
for examples.  Renames
Control.Effect.Void
,Void
, andVoidC
toControl.Effect.Pure
,Pure
, andPureC
respectively. This is a backwardsincompatible change for code mentioningVoidC
; it should be updated to referencePureC
instead.
Deprecations
Eff
andinterpret
, in favour of computing directly in the carriers. This enables the compiler to perform significant optimizations; see the benchmarks for details. Handlers can simply remove theEff
wrapping the carrier type & any use ofinterpret
. As above, we also recommend compiling withWredundantconstraints
as many of these can now be removed.ret
, in favor ofpure
orreturn
.handleEither
,handleReader
,handleState
,handleSum
, andhandleTraversable
in favour of composing carrier types directly. Carriers can be composed from other carriers andeff
defined withhandleCoercible
; and other definitions can usehandlePure
&handle
directly.
All deprecated APIs will be removed in the next release.
Other changes
 Adds a lazy
State
carrier inControl.Effect.State.Lazy
 Rewrites
CutC
using an approach related toNonDetC
, with the addition of a continuation to distinguishempty
fromcutfail
.  Rewrites
CullC
usingListC
andReaderC
.  Moves
OnceC
fromControl.Effect.NonDet
toControl.Effect.Cull
to avoid cyclic dependencies.  Adds a
runCutAll
handler forCut
effects, returning a collection of all results.
0.2.0.2
 Loosens the bounds on QuickCheck to accommodate 2.x.
0.2.0.1
 Fixes the benchmarks, and builds them in CI to avoid regressing them again.
0.2.0.0
 Adds
listen
,listens
, andcensor
operations toWriter
.  Provides explicit type parameters to
run
style functions inState
,Reader
,Writer
, andError
. This is a backwardsincompatible change for clients using these functions in combination with visible type applications.  Adds benchmarks of
WriterC
/VoidC
wrapped withEff
against their unwrapped counterparts.  Adds
Functor
,Applicative
, andMonad
instances forWriterC
.  Adds
Functor
,Applicative
, andMonad
instances forVoidC
.  Fixes a space leak with
WriterC
.  Removes the
Functor
constraint onasks
andgets
.  Adds
bracketOnError
,finally
, andonException
toResource
.  Adds
sendM
toLift
.
0.1.2.1
 Loosens the bounds on QuickCheck to accommodate 0.12.
0.1.2.0
 Adds support for ghc 8.6.2, courtesy of @jkachmar.
 Adds a
Cut
effect which adds committed choice to nondeterminism.  Adds a
Cull
effect which adds pruning to nondeterminism.  Adds an example of using
NonDet
,Cut
, and a character parser effect to define parsers.  Fixes the table of contents links in the README.
0.1.1.0
 Adds a
runNonDetOnce
handler which terminates immediately upon finding a solution.
0.1.0.0
Initial release.