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Files
fp-go/monoid/alt.go
Dr. Carsten Leue 5f25317f97 fix: provide AltMonoid
Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>
2023-10-06 21:50:22 +02:00

59 lines
1.3 KiB
Go

// Copyright (c) 2023 IBM Corp.
// All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package monoid
import (
S "github.com/IBM/fp-go/semigroup"
)
func AlternativeMonoid[A, HKTA, HKTFA any, LAZYHKTA ~func() HKTA](
fof func(A) HKTA,
fmap func(HKTA, func(A) func(A) A) HKTFA,
fap func(HKTFA, HKTA) HKTA,
falt func(HKTA, LAZYHKTA) HKTA,
m Monoid[A],
) Monoid[HKTA] {
sg := ApplicativeMonoid(fof, fmap, fap, m)
return MakeMonoid(
func(first, second HKTA) HKTA {
snd := func() HKTA { return second }
return falt(sg.Concat(first, second), func() HKTA {
return falt(first, snd)
})
},
sg.Empty(),
)
}
func AltMonoid[HKTA any, LAZYHKTA ~func() HKTA](
fzero LAZYHKTA,
falt func(HKTA, LAZYHKTA) HKTA,
) Monoid[HKTA] {
return MakeMonoid(
S.AltSemigroup(falt).Concat,
fzero(),
)
}