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46 lines
1.3 KiB
Go
46 lines
1.3 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 generic
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import (
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F "github.com/IBM/fp-go/function"
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O "github.com/IBM/fp-go/option"
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P "github.com/IBM/fp-go/pair"
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)
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func apTuple[A, B any](t P.Pair[func(A) B, A]) P.Pair[B, A] {
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return P.MakePair(P.Head(t)(P.Tail(t)), P.Tail(t))
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}
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func Scan[GV ~func() O.Option[P.Pair[GV, V]], GU ~func() O.Option[P.Pair[GU, U]], FCT ~func(V, U) V, U, V any](f FCT, initial V) func(ma GU) GV {
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// pre-declare to avoid cyclic reference
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var m func(GU) func(V) GV
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recurse := func(ma GU, current V) GV {
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return F.Nullary2(
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ma,
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O.Map(F.Flow2(
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P.BiMap(m, F.Bind1st(f, current)),
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apTuple[V, GV],
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)),
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)
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}
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m = F.Curry2(recurse)
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return F.Bind2nd(recurse, initial)
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}
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