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30 lines
975 B
Go
30 lines
975 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 lambda
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// Y is the Y-combinator based on https://dreamsongs.com/Files/WhyOfY.pdf
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func Y[Endo ~func(RecFct) RecFct, RecFct ~func(T) R, T, R any](f Endo) RecFct {
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type internal[RecFct ~func(T) R, T, R any] func(internal[RecFct, T, R]) RecFct
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g := func(h internal[RecFct, T, R]) RecFct {
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return func(t T) R {
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return f(h(h))(t)
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}
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}
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return g(g)
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}
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