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100 lines
2.0 KiB
Go
100 lines
2.0 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 magma
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type Magma[A any] interface {
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Concat(x A, y A) A
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}
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type magma[A any] struct {
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c func(A, A) A
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}
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func (m magma[A]) Concat(x A, y A) A {
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return m.c(x, y)
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}
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func MakeMagma[A any](c func(A, A) A) Magma[A] {
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return magma[A]{c: c}
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}
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func Reverse[A any](m Magma[A]) Magma[A] {
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return MakeMagma(func(x A, y A) A {
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return m.Concat(y, x)
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})
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}
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func filterFirst[A any](p func(A) bool, c func(A, A) A, x A, y A) A {
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if p(x) {
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return c(x, y)
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}
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return y
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}
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func filterSecond[A any](p func(A) bool, c func(A, A) A, x A, y A) A {
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if p(y) {
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return c(x, y)
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}
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return x
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}
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func FilterFirst[A any](p func(A) bool) func(Magma[A]) Magma[A] {
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return func(m Magma[A]) Magma[A] {
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c := m.Concat
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return MakeMagma(func(x A, y A) A {
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return filterFirst(p, c, x, y)
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})
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}
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}
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func FilterSecond[A any](p func(A) bool) func(Magma[A]) Magma[A] {
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return func(m Magma[A]) Magma[A] {
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c := m.Concat
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return MakeMagma(func(x, y A) A {
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return filterSecond(p, c, x, y)
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})
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}
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}
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func first[A any](x, _ A) A {
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return x
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}
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func second[A any](_, y A) A {
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return y
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}
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func First[A any]() Magma[A] {
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return MakeMagma(first[A])
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}
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func Second[A any]() Magma[A] {
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return MakeMagma(second[A])
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}
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func endo[A any](f func(A) A, c func(A, A) A, x, y A) A {
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return c(f(x), f(y))
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}
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func Endo[A any](f func(A) A) func(Magma[A]) Magma[A] {
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return func(m Magma[A]) Magma[A] {
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c := m.Concat
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return MakeMagma(func(x A, y A) A {
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return endo(f, c, x, y)
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})
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}
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}
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