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samber
🦄 Monads and popular FP abstractions, powered by Go 1.18+ Generics (Option, Result, Either...)
mo - Monads
🦄 samber/mo brings monads and popular FP abstractions to Go projects. samber/mo uses the recent Go 1.18+ Generics.
Inspired by:
- Scala
- Rust
- FP-TS
See also:
- samber/lo: A Lodash-style Go library based on Go 1.18+ Generics
- samber/do: A dependency injection toolkit based on Go 1.18+ Generics
Why this name?
I love short name for such utility library. This name is similar to "Monad Go" and no Go package currently uses this name.
💡 Features
We currently support the following data types:
-
Option[T](Maybe) -
Result[T] -
Either[A, B] -
Future[T] -
IO[T] -
IOEither[T] -
Task[T] -
TaskEither[T] -
State[S, A]
🚀 Install
go get github.com/samber/mo@v1
This library is v1 and follows SemVer strictly.
No breaking changes will be made to exported APIs before v2.0.0.
💡 Quick start
You can import mo using:
import (
"github.com/samber/mo"
)
Then use one of the helpers below:
option1 := mo.Some(42)
// Some(42)
option1.
FlatMap(func (value int) Option[int] {
return Some(value*2)
}).
FlatMap(func (value int) Option[int] {
return Some(value%2)
}).
FlatMap(func (value int) Option[int] {
return Some(value+21)
}).
OrElse(1234)
// 21
option2 := mo.None[int]()
// None
option2.OrElse(1234)
// 1234
option3 := option1.Match(
func(i int) (int, bool) {
// when value is present
return i * 2, true
},
func() (int, bool) {
// when value is absent
return 0, false
},
)
// Some(42)
More examples in documentation.
🤠 Documentation and examples
GoDoc: https://godoc.org/github.com/samber/mo
Option[T any]
Option is a container for an optional value of type T. If value exists, Option is of type Some. If the value is absent, Option is of type None.
Constructors:
Methods:
-
.IsPresent()doc -
.IsAbsent()doc -
.Size()doc -
.Get()doc -
.MustGet()doc -
.OrElse()doc -
.OrEmpty()doc -
.ForEach()doc -
.Match()doc -
.Map()doc -
.MapNone()doc -
.FlatMap()doc
Result[T any]
Result respresent a result of an action having one of the following output: success or failure. An instance of Result is an instance of either Ok or Err. It could be compared to Either[error, T].
Constructors:
Methods:
-
.IsOk()doc -
.IsError()doc -
.Error()doc -
.Get()doc -
.MustGet()doc -
.OrElse()doc -
.OrEmpty()doc -
.ToEither()doc -
.ForEach()doc -
.Match()doc -
.Map()doc -
.MapErr()doc -
.FlatMap()doc
Either[L any, R any]
Either respresents a value of 2 possible types. An instance of Either is an instance of either A or B.
Constructors:
Methods:
-
.IsLeft()doc -
.IsRight()doc -
.Left()doc -
.Right()doc -
.MustLeft()doc -
.MustRight()doc -
.LeftOrElse()doc -
.RightOrElse()doc -
.LeftOrEmpty()doc -
.RightOrEmpty()doc -
.Swap()doc -
.ForEach()doc -
.Match()doc -
.MapLeft()doc -
.MapRight()doc
Future[T any]
Future represents a value which may or may not currently be available, but will be available at some point, or an exception if that value could not be made available.
Constructors:
-
mo.NewFuture()doc
Methods:
IO[T any]
IO represents a non-deterministic synchronous computation that can cause side effects, yields a value of type R and never fails.
Constructors:
Methods:
-
.Run()doc
IOEither[T any]
IO represents a non-deterministic synchronous computation that can cause side effects, yields a value of type R and can fail.
Constructors:
-
mo.NewIOEither()doc -
mo.NewIOEither1()doc -
mo.NewIOEither2()doc -
mo.NewIOEither3()doc -
mo.NewIOEither4()doc -
mo.NewIOEither5()doc
Methods:
-
.Run()doc
Task[T any]
Task represents a non-deterministic asynchronous computation that can cause side effects, yields a value of type R and never fails.
Constructors:
-
mo.NewTask()doc -
mo.NewTask1()doc -
mo.NewTask2()doc -
mo.NewTask3()doc -
mo.NewTask4()doc -
mo.NewTask5()doc -
mo.NewTaskFromIO()doc -
mo.NewTaskFromIO1()doc -
mo.NewTaskFromIO2()doc -
mo.NewTaskFromIO3()doc -
mo.NewTaskFromIO4()doc -
mo.NewTaskFromIO5()doc
Methods:
-
.Run()doc
TaskEither[T any]
TaskEither represents a non-deterministic asynchronous computation that can cause side effects, yields a value of type R and can fail.
Constructors:
Methods:
State[S any, A any]
State represents a function (S) -> (A, S), where S is state, A is result.
Constructors:
Methods:
🛩 Benchmark
// @TODO
This library does not use reflect package. We don't expect overhead.
🤝 Contributing
- Ping me on twitter @samuelberthe (DMs, mentions, whatever :))
- Fork the project
- Fix open issues or request new features
Don't hesitate ;)
With Docker
docker-compose run --rm dev
Without Docker
# Install some dev dependencies
make tools
# Run tests
make test
# or
make watch-test
👤 Authors
- Samuel Berthe
💫 Show your support
Give a ⭐️ if this project helped you!
📝 License
Copyright © 2022 Samuel Berthe.
This project is MIT licensed.
samber