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132 lines
4.5 KiB
Go
132 lines
4.5 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 record
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import (
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Mo "github.com/IBM/fp-go/v2/monoid"
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G "github.com/IBM/fp-go/v2/record/generic"
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)
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// Do creates an empty context of type [S] to be used with the [Bind] operation.
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// This is the starting point for do-notation style composition.
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//
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// Example:
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//
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// type State struct {
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// Name string
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// Count int
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// }
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// result := record.Do[string, State]()
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func Do[K comparable, S any]() map[K]S {
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return G.Do[map[K]S, K, S]()
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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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// This enables sequential composition where each step can depend on the results of previous steps.
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// For records, this merges values by key.
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//
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// The setter function takes the result of the computation and returns a function that
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// updates the context from S1 to S2.
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//
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// Example:
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//
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// type State struct {
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// Name string
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// Count int
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// }
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//
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// result := F.Pipe2(
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// record.Do[string, State](),
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// record.Bind(monoid.Record[string, State]())(
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// func(name string) func(State) State {
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// return func(s State) State { s.Name = name; return s }
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// },
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// func(s State) map[string]string {
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// return map[string]string{"a": "Alice", "b": "Bob"}
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// },
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// ),
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// record.Bind(monoid.Record[string, State]())(
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// func(count int) func(State) State {
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// return func(s State) State { s.Count = count; return s }
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// },
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// func(s State) map[string]int {
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// // This can access s.Name from the previous step
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// return map[string]int{"a": len(s.Name), "b": len(s.Name) * 2}
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// },
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// ),
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// )
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func Bind[S1, T any, K comparable, S2 any](m Mo.Monoid[map[K]S2]) func(setter func(T) func(S1) S2, f func(S1) map[K]T) func(map[K]S1) map[K]S2 {
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return G.Bind[map[K]S1, map[K]S2, map[K]T, K, S1, S2, T](m)
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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, T any, K comparable, S2 any](
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setter func(T) func(S1) S2,
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f func(S1) T,
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) func(map[K]S1) map[K]S2 {
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return G.Let[map[K]S1, map[K]S2, K, 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, T any, K comparable, S2 any](
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setter func(T) func(S1) S2,
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b T,
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) func(map[K]S1) map[K]S2 {
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return G.LetTo[map[K]S1, map[K]S2, K, 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, K comparable](setter func(T) S1) func(map[K]T) map[K]S1 {
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return G.BindTo[map[K]S1, map[K]T, K, 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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// Name string
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// Count int
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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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// names := map[string]string{"a": "Alice", "b": "Bob"}
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// counts := map[string]int{"a": 10, "b": 20}
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//
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// result := F.Pipe2(
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// record.Do[string, State](),
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// record.ApS(monoid.Record[string, State]())(
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// func(name string) func(State) State {
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// return func(s State) State { s.Name = name; return s }
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// },
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// names,
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// ),
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// record.ApS(monoid.Record[string, State]())(
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// func(count int) func(State) State {
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// return func(s State) State { s.Count = count; return s }
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// },
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// counts,
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// ),
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// ) // map[string]State{"a": {Name: "Alice", Count: 10}, "b": {Name: "Bob", Count: 20}}
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func ApS[S1, T any, K comparable, S2 any](m Mo.Monoid[map[K]S2]) func(setter func(T) func(S1) S2, fa map[K]T) func(map[K]S1) map[K]S2 {
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return G.ApS[map[K]S1, map[K]S2, map[K]T, K, S1, S2, T](m)
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}
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