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53 lines
1.7 KiB
Go
53 lines
1.7 KiB
Go
// Copyright (c) 2023 IBM Corp.
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// All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ord
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import (
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F "github.com/IBM/fp-go/function"
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M "github.com/IBM/fp-go/monoid"
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S "github.com/IBM/fp-go/semigroup"
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)
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// Semigroup implements a two level ordering
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func Semigroup[A any]() S.Semigroup[Ord[A]] {
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return S.MakeSemigroup(func(first, second Ord[A]) Ord[A] {
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return FromCompare(func(a, b A) int {
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ox := first.Compare(a, b)
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if ox != 0 {
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return ox
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}
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return second.Compare(a, b)
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})
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})
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}
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// Monoid implements a two level ordering such that
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// - its `Concat(ord1, ord2)` operation will order first by `ord1`, and then by `ord2`
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// - its `Empty` value is an `Ord` that always considers compared elements equal
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func Monoid[A any]() M.Monoid[Ord[A]] {
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return M.MakeMonoid(Semigroup[A]().Concat, FromCompare(F.Constant2[A, A](0)))
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}
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// MaxSemigroup returns a semigroup where `concat` will return the maximum, based on the provided order.
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func MaxSemigroup[A any](O Ord[A]) S.Semigroup[A] {
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return S.MakeSemigroup(Max(O))
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}
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// MaxSemigroup returns a semigroup where `concat` will return the minimum, based on the provided order.
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func MinSemigroup[A any](O Ord[A]) S.Semigroup[A] {
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return S.MakeSemigroup(Min(O))
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}
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