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70 lines
2.6 KiB
Go
70 lines
2.6 KiB
Go
// Copyright (c) 2025 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 option
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import (
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F "github.com/IBM/fp-go/v2/function"
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)
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// Sequence converts an Option of some higher kinded type into the higher kinded type of an Option.
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// This is a generic sequencing operation that works with any applicative functor.
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//
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// Parameters:
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// - mof: wraps an Option in the target higher kinded type
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// - mmap: maps a function over the higher kinded type
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//
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// Example (conceptual - typically used with other monadic types):
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//
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// // Sequencing Option[IO[A]] to IO[Option[A]]
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// result := Sequence[int, IO[int], IO[Option[int]]](
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// func(opt Option[int]) IO[Option[int]] { return IO.Of(opt) },
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// func(f func(int) Option[int]) func(IO[int]) IO[Option[int]] { ... },
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// )
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func Sequence[A, HKTA, HKTOA any](
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mof func(Option[A]) HKTOA,
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mmap func(Kleisli[A, A]) func(HKTA) HKTOA,
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) func(Option[HKTA]) HKTOA {
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return Fold(F.Nullary2(None[A], mof), mmap(Some[A]))
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}
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// Traverse converts an Option by applying a function that produces a higher kinded type,
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// then sequences the result. This combines mapping and sequencing in one operation.
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//
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// Parameters:
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// - mof: wraps an Option in the target higher kinded type
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// - mmap: maps a function over the higher kinded type
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//
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// Returns a function that takes a transformation function and an Option, producing
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// the higher kinded type containing an Option.
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//
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// Example (conceptual - typically used with other monadic types):
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//
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// // Traversing Option[A] with a function A -> IO[B] to get IO[Option[B]]
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// result := Traverse[int, string, IO[string], IO[Option[string]]](
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// func(opt Option[string]) IO[Option[string]] { return IO.Of(opt) },
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// func(f func(string) Option[string]) func(IO[string]) IO[Option[string]] { ... },
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// )
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func Traverse[A, B, HKTB, HKTOB any](
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mof func(Option[B]) HKTOB,
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mmap func(Kleisli[B, B]) func(HKTB) HKTOB,
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) func(func(A) HKTB) func(Option[A]) HKTOB {
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onNone := F.Nullary2(None[B], mof)
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onSome := mmap(Some[B])
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return func(f func(A) HKTB) func(Option[A]) HKTOB {
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return Fold(onNone, F.Flow2(f, onSome))
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}
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}
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