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27 lines
878 B
Go
27 lines
878 B
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 eq
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// Contramap implements an Equals predicate based on a mapping
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func Contramap[A, B any](f func(b B) A) func(Eq[A]) Eq[B] {
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return func(fa Eq[A]) Eq[B] {
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equals := fa.Equals
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return FromEquals(func(x, y B) bool {
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return equals(f(x), f(y))
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})
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}
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}
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