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105 lines
3.5 KiB
Go
105 lines
3.5 KiB
Go
// Copyright (c) 2023 - 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 readereither
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import (
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"context"
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G "github.com/IBM/fp-go/v2/readereither/generic"
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)
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// Bind creates an empty context of type [S] to be used with the [Bind] operation
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func Do[S any](
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empty S,
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) ReaderEither[S] {
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return G.Do[ReaderEither[S], context.Context, error, S](empty)
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}
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// Bind attaches the result of a computation to a context [S1] to produce a context [S2]
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func Bind[S1, S2, T any](
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setter func(T) func(S1) S2,
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f func(S1) ReaderEither[T],
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) func(ReaderEither[S1]) ReaderEither[S2] {
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return G.Bind[ReaderEither[S1], ReaderEither[S2], ReaderEither[T], context.Context, error, S1, S2, T](setter, f)
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}
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// Let attaches the result of a computation to a context [S1] to produce a context [S2]
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func Let[S1, S2, T any](
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setter func(T) func(S1) S2,
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f func(S1) T,
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) func(ReaderEither[S1]) ReaderEither[S2] {
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return G.Let[ReaderEither[S1], ReaderEither[S2], context.Context, error, S1, S2, T](setter, f)
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}
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// LetTo attaches the a value to a context [S1] to produce a context [S2]
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func LetTo[S1, S2, T any](
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setter func(T) func(S1) S2,
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b T,
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) func(ReaderEither[S1]) ReaderEither[S2] {
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return G.LetTo[ReaderEither[S1], ReaderEither[S2], context.Context, error, S1, S2, T](setter, b)
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}
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// BindTo initializes a new state [S1] from a value [T]
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func BindTo[S1, T any](
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setter func(T) S1,
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) func(ReaderEither[T]) ReaderEither[S1] {
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return G.BindTo[ReaderEither[S1], ReaderEither[T], context.Context, error, S1, T](setter)
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}
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// ApS attaches a value to a context [S1] to produce a context [S2] by considering
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// the context and the value concurrently (using Applicative rather than Monad).
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// This allows independent computations to be combined without one depending on the result of the other.
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//
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// Unlike Bind, which sequences operations, ApS can be used when operations are independent
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// and can conceptually run in parallel.
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//
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// Example:
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//
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// type State struct {
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// UserID string
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// TenantID string
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// }
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//
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// // These operations are independent and can be combined with ApS
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// getUserID := func(ctx context.Context) either.Either[error, string] {
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// return either.Right[error](ctx.Value("userID").(string))
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// }
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// getTenantID := func(ctx context.Context) either.Either[error, string] {
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// return either.Right[error](ctx.Value("tenantID").(string))
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// }
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//
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// result := F.Pipe2(
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// readereither.Do(State{}),
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// readereither.ApS(
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// func(uid string) func(State) State {
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// return func(s State) State { s.UserID = uid; return s }
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// },
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// getUserID,
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// ),
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// readereither.ApS(
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// func(tid string) func(State) State {
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// return func(s State) State { s.TenantID = tid; return s }
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// },
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// getTenantID,
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// ),
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// )
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func ApS[S1, S2, T any](
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setter func(T) func(S1) S2,
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fa ReaderEither[T],
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) func(ReaderEither[S1]) ReaderEither[S2] {
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return G.ApS[ReaderEither[S1], ReaderEither[S2], ReaderEither[T], context.Context, error, S1, S2, T](setter, fa)
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}
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