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🦄 Monads and popular FP abstractions, powered by Go 1.18+ Generics (Option, Result, Either...)
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samber/mo
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🦄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 loveshort name for such utility library. This name is similar to "Monad Go" and no Go package uses this name.
We currently support the following data types:
Option[T](Maybe)Result[T]Either[A, B]EitherX[T1, ..., TX](With X between 3 and 5)Future[T]IO[T]IOEither[T]Task[T]TaskEither[T]State[S, A]
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.
This library has no dependencies except the Go std lib.
You can importmo using:
import ("github.com/samber/mo")
Then use one of the helpers below:
option1:=mo.Some(42)// Some(42)option1.FlatMap(func (valueint)Option[int] {returnSome(value*2) }).FlatMap(func (valueint)Option[int] {returnSome(value%2) }).FlatMap(func (valueint)Option[int] {returnSome(value+21) }).OrElse(1234)// 21option2:=mo.None[int]()// Noneoption2.OrElse(1234)// 1234option3:=option1.Match(func(iint) (int,bool) {// when value is presentreturni*2,true },func() (int,bool) {// when value is absentreturn0,false },)// Some(42)
More examples indocumentation.
I cannot recommend it, but in case you are too lazy for repeatingmo. everywhere, you can import the entire library into the namespace.
import ( ."github.com/samber/mo")
I take no responsibility on this junk. 😁 💩
GoDoc: https://godoc.org/github.com/samber/mo
Option is a container for an optional value of typeT. If value exists,Option is of typeSome. If the value is absent,Option is of typeNone.
Implements:
mo.Foldable[T, U]
Constructors:
mo.Some()doc -playmo.None()doc -playmo.TupleToOption()doc -playmo.EmptyableToOption()doc -playmo.PointerToOption()doc -play
Methods:
.IsPresent()doc -play.IsAbsent()doc -play.Size()doc -play.Get()doc -play.MustGet()doc -play.OrElse()doc -play.OrEmpty()doc -play.ToPointer()doc -play.ForEach()doc.Match()doc -play.Map()doc -play.MapNone()doc -play.FlatMap()doc -play.MarshalJSON()doc.UnmarshalJSON()doc.MarshalText()doc.UnmarshalText()doc.MarshalBinary()doc.UnmarshalBinary()doc.GobEncode()doc.GobDecode()doc.Scan()doc.Value()doc
Other:
mo.Fold[T, U, R any](f Foldable[T, U], successFunc func(U) R, failureFunc func(T) R) Rdoc
Result respresent a result of an action having one of the following output: success or failure. An instance ofResult is an instance of eitherOk orErr. It could be compared toEither[error, T].
Implements:
mo.Foldable[T, U]
Constructors:
Methods:
.IsOk()doc -play.IsError()doc -play.Error()doc -play.Get()doc -play.MustGet()doc -play.OrElse()doc -play.OrEmpty()doc -play.ToEither()doc -play.ForEach()doc.Match()doc -play.Map()doc -play.MapErr()doc -play.FlatMap()doc -play
Other:
mo.Fold[T, U, R any](f Foldable[T, U], successFunc func(U) R, failureFunc func(T) R) Rdocmo.Do[T any](fn func() T) (result mo.Result[T])doc
Either represents a value of 2 possible types. An instance ofEither is an instance of eitherA orB.
Implements:
mo.Foldable[T, U]
Constructors:
Methods:
.IsLeft()doc.IsRight()doc.Left()doc.Right()doc.MustLeft()doc.MustRight()doc.Unpack()doc.LeftOrElse()doc.RightOrElse()doc.LeftOrEmpty()doc.RightOrEmpty()doc.Swap()doc.ForEach()doc.Match()doc.MapLeft()doc.MapRight()doc
Other:
mo.Fold[T, U, R any](f Foldable[T, U], successFunc func(U) R, failureFunc func(T) R) Rdoc
EitherX respresents a value of X possible types. For example, anEither3 value is eitherT1,T2 orT3.
Constructors:
mo.NewEitherXArgY()doc. Eg:mo.NewEither3Arg1[A, B, C](A)mo.NewEither3Arg2[A, B, C](B)mo.NewEither3Arg3[A, B, C](C)mo.NewEither4Arg1[A, B, C, D](A)mo.NewEither4Arg2[A, B, C, D](B)- ...
Methods:
.IsArgX()doc.ArgX()doc.MustArgX()doc.Unpack()doc.ArgXOrElse()doc.ArgXOrEmpty()doc.ForEach()doc.Match()doc.MapArgX()doc
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 represents a non-deterministic synchronous computation that can cause side effects, yields a value of typeR and never fails.
Constructors:
Methods:
.Run()doc
IO represents a non-deterministic synchronous computation that can cause side effects, yields a value of typeR and can fail.
Constructors:
mo.NewIOEither()docmo.NewIOEither1()docmo.NewIOEither2()docmo.NewIOEither3()docmo.NewIOEither4()docmo.NewIOEither5()doc
Methods:
.Run()doc
Task represents a non-deterministic asynchronous computation that can cause side effects, yields a value of typeR and never fails.
Constructors:
mo.NewTask()docmo.NewTask1()docmo.NewTask2()docmo.NewTask3()docmo.NewTask4()docmo.NewTask5()docmo.NewTaskFromIO()docmo.NewTaskFromIO1()docmo.NewTaskFromIO2()docmo.NewTaskFromIO3()docmo.NewTaskFromIO4()docmo.NewTaskFromIO5()doc
Methods:
.Run()doc
TaskEither represents a non-deterministic asynchronous computation that can cause side effects, yields a value of typeR and can fail.
Constructors:
Methods:
State represents a function(S) -> (A, S), whereS is state,A is result.
Constructors:
Methods:
Foldable represents a type that can be folded into a single value based on its state.
mo.Fold[T, U, R any](f Foldable[T, U], successFunc func(U) R, failureFunc func(T) R) Rdoc
// @TODO
This library does not usereflect package. We don't expect overhead.
- Ping me on Twitter@samuelberthe (DMs, mentions, whatever :))
- Fork theproject
- Fixopen issues or request new features
Don't hesitate ;)
docker-compose run --rm dev
# Install some dev dependenciesmake tools# Run testsmaketest# ormake watch-test
Give a ⭐️ if this project helped you!
Copyright © 2022Samuel Berthe.
This project isMIT licensed.
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🦄 Monads and popular FP abstractions, powered by Go 1.18+ Generics (Option, Result, Either...)