# mo - Monads [](https://github.com/samber/mo/releases)  [](https://pkg.go.dev/github.com/samber/mo)  [](https://goreportcard.com/report/github.com/samber/mo) [](https://codecov.io/gh/samber/mo) [](./LICENSE) **\`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/ro](https://github.com/samber/ro): Reactive Programming for Go: declarative and composable API for event-driven applications - [samber/lo](https://github.com/samber/lo): A Lodash-style Go library based on Go 1.18+ Generics - [samber/do](https://github.com/samber/do): A dependency injection toolkit based on Go 1.18+ Generics - [samber/cc-skills-golang](https://github.com/samber/cc-skills-golang): AI Agent Skills for Golang ---- ----  **Why this name?** I love **short name** for such utility library. This name is similar to "Monad Go" and no Go package uses this name. ## Features 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]\` ## Install \`\`\`sh go get github.com/samber/mo@v1 # AI Agent Skill npx skills add https://github.com/samber/cc-skills-golang --skill golang-samber-mo \`\`\` 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. ## Quick start You can import \`mo\` using: \`\`\`go import ( "github.com/samber/mo" ) \`\`\` Quick example using the \`option\` sub-package \`Pipe3\` to compose transformations: \`\`\`go import ( "github.com/samber/mo" "github.com/samber/mo/option" ) out := option.Pipe3( mo.Some(21), option.Map(func(v int) int \{ return v * 2 \}), option.FlatMap(func(v int) mo.Option[int] \{ return mo.None[int]() \}), option.Map(func(v int) int \{ return v + 21 \}), ) // out == None[int] \`\`\` Then use one of the helpers below: \`\`\`go 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](https://godoc.org/github.com/samber/mo). ### Tips for lazy developers I cannot recommend it, but in case you are too lazy for repeating \`mo.\` everywhere, you can import the entire library into the namespace. \`\`\`go import ( . "github.com/samber/mo" ) \`\`\` I take no responsibility on this junk. ## Documentation and examples [GoDoc: https://godoc.org/github.com/samber/mo](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\`. Implements: - \`mo.Foldable[T, U]\` Constructors: - \`mo.Some()\` [doc](https://pkg.go.dev/github.com/samber/mo#Some) - [play](https://go.dev/play/p/iqz2n9n0tDM) - \`mo.None()\` [doc](https://pkg.go.dev/github.com/samber/mo#None) - [play](https://go.dev/play/p/yYQPsYCSYlD) - \`mo.TupleToOption()\` [doc](https://pkg.go.dev/github.com/samber/mo#TupleToOption) - [play](https://go.dev/play/p/gkrg2pZwOty) - \`mo.EmptyableToOption()\` [doc](https://pkg.go.dev/github.com/samber/mo#EmptyableToOption) - [play](https://go.dev/play/p/GSpQQ-q-UES) - \`mo.PointerToOption()\` [doc](https://pkg.go.dev/github.com/samber/mo#PointerToOption) - [play](https://go.dev/play/p/yPVMj4DUb-I) Methods: - \`.IsPresent()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.IsPresent) - [play](https://go.dev/play/p/nDqIaiihyCA) - \`.IsSome()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.IsSome) - [play](https://go.dev/play/p/DyvGRy7fP9m) - \`.IsAbsent()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.IsAbsent) - [play](https://go.dev/play/p/23e2zqyVOQm) - \`.IsNone()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.IsNone) - [play](https://go.dev/play/p/EdqxKhborIP) - \`.Size()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.Size) - [play](https://go.dev/play/p/7ixCNG1E9l7) - \`.Get()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.Get) - [play](https://go.dev/play/p/0-JBa1usZRT) - \`.MustGet()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.MustGet) - [play](https://go.dev/play/p/RVBckjdi5WR) - \`.OrElse()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.OrElse) - [play](https://go.dev/play/p/TrGByFWCzXS) - \`.OrEmpty()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.OrEmpty) - [play](https://go.dev/play/p/SpSUJcE-tQm) - \`.ToPointer()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.ToPointer) - [play](https://go.dev/play/p/KJc2Pv3KNPW) - \`.ForEach()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.ForEach) - \`.Match()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.Match) - [play](https://go.dev/play/p/1V6st3LDJsM) - \`.Map()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.Map) - [play](https://go.dev/play/p/mvfP3pcP_eJ) - \`.MapNone()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.MapNone) - [play](https://go.dev/play/p/_KaHWZ6Q17b) - \`.MapValue()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.MapValue) - \`.FlatMap()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.FlatMap) - [play](https://go.dev/play/p/OXO-zJx6n5r) - \`.MarshalJSON()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.MarshalJSON) - \`.UnmarshalJSON()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.UnmarshalJSON) - \`.MarshalText()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.MarshalText) - \`.UnmarshalText()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.UnmarshalText) - \`.MarshalBinary()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.MarshalBinary) - \`.UnmarshalBinary()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.UnmarshalBinary) - \`.GobEncode()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.GobEncode) - \`.GobDecode()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.GobDecode) - \`.Scan()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.Scan) - \`.Value()\` [doc](https://pkg.go.dev/github.com/samber/mo#Option.Value) Other: - \`mo.Fold[T, U, R any](f Foldable[T, U], successFunc func(U) R, failureFunc func(T) R) R\` [doc](https://pkg.go.dev/github.com/samber/mo#Fold) Sub-package \`option\` (transformations and pipes): - \`option.Map()()\` [doc](https://pkg.go.dev/github.com/samber/mo/option#Map) - \`option.FlatMap()()\` [doc](https://pkg.go.dev/github.com/samber/mo/option#FlatMap) - \`option.Match()()\` [doc](https://pkg.go.dev/github.com/samber/mo/option#Match) - \`option.FlatMatch()()\` [doc](https://pkg.go.dev/github.com/samber/mo/option#FlatMatch) - \`option.Pipe1..Pipe10()\` [docs](https://pkg.go.dev/github.com/samber/mo/option#Pipe1) ### 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]\`. Implements: - \`mo.Foldable[T, U]\` Constructors: - \`mo.Ok()\` [doc](https://pkg.go.dev/github.com/samber/mo#Ok) - [play](https://go.dev/play/p/PDwADdzNoyZ) - \`mo.Err()\` [doc](https://pkg.go.dev/github.com/samber/mo#Err) - [play](https://go.dev/play/p/PDwADdzNoyZ) - \`mo.Errf()\` [doc](https://pkg.go.dev/github.com/samber/mo#Errf) - [play](https://go.dev/play/p/N43w92SM-Bs) - \`mo.TupleToResult()\` [doc](https://pkg.go.dev/github.com/samber/mo#TupleToResult) - [play](https://go.dev/play/p/KWjfqQDHQwa) - \`mo.Try()\` [doc](https://pkg.go.dev/github.com/samber/mo#Try) - [play](https://go.dev/play/p/ilOlQx-Mx42) Methods: - \`.IsOk()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.IsOk) - [play](https://go.dev/play/p/sfNvBQyZfgU) - \`.IsError()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.IsError) - [play](https://go.dev/play/p/xkV9d464scV) - \`.Error()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.Error) - [play](https://go.dev/play/p/CSkHGTyiXJ5) - \`.Get()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.Get) - [play](https://go.dev/play/p/8KyX3z6TuNo) - \`.MustGet()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.MustGet) - [play](https://go.dev/play/p/8LSlndHoTAE) - \`.OrElse()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.OrElse) - [play](https://go.dev/play/p/MN_ULx0soi6) - \`.OrEmpty()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.OrEmpty) - [play](https://go.dev/play/p/rdKtBmOcMLh) - \`.ToEither()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.ToEither) - [play](https://go.dev/play/p/Uw1Zz6b952q) - \`.ForEach()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.ForEach) - [play](https://go.dev/play/p/Z59EvNdWoRx) - \`.Match()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.Match) - [play](https://go.dev/play/p/-_eFaLJ31co) - \`.Map()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.Map) - [play](https://go.dev/play/p/-ndpN_b_OSc) - \`.MapValue()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.MapValue) - [play](https://go.dev/play/p/qyyjUP4XbK2) - \`.MapErr()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.MapErr) - [play](https://go.dev/play/p/WraZixg9GGf) - \`.FlatMap()\` [doc](https://pkg.go.dev/github.com/samber/mo#Result.FlatMap) - [play](https://go.dev/play/p/Ud5QjZOqg-7) Other: - \`mo.Fold[T, U, R any](f Foldable[T, U], successFunc func(U) R, failureFunc func(T) R) R\` [doc](https://pkg.go.dev/github.com/samber/mo#Fold) - \`mo.Do[T any](fn func() T) (result mo.Result[T])\` [doc](https://pkg.go.dev/github.com/samber/mo#Do) Sub-package \`result\` (transformations and pipes): - \`result.Map()()\` [doc](https://pkg.go.dev/github.com/samber/mo/result#Map) - \`result.FlatMap()()\` [doc](https://pkg.go.dev/github.com/samber/mo/result#FlatMap) - \`result.Match()()\` [doc](https://pkg.go.dev/github.com/samber/mo/result#Match) - \`result.FlatMatch()()\` [doc](https://pkg.go.dev/github.com/samber/mo/result#FlatMatch) - \`result.Pipe1..Pipe10()\` [docs](https://pkg.go.dev/github.com/samber/mo/result#Pipe1) ### Either[L any, R any] \`Either\` represents a value of 2 possible types. An instance of \`Either\` is an instance of either \`A\` or \`B\`. Implements: - \`mo.Foldable[T, U]\` Constructors: - \`mo.Left()\` [doc](https://pkg.go.dev/github.com/samber/mo#Left) - \`mo.Right()\` [doc](https://pkg.go.dev/github.com/samber/mo#Right) Methods: - \`.IsLeft()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.IsLeft) - \`.IsRight()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.IsRight) - \`.Left()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.Left) - \`.Right()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.Right) - \`.MustLeft()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.MustLeft) - \`.MustRight()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.MustRight) - \`.Unpack()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.Unpack) - \`.LeftOrElse()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.LeftOrElse) - \`.RightOrElse()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.RightOrElse) - \`.LeftOrEmpty()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.LeftOrEmpty) - \`.RightOrEmpty()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.RightOrEmpty) - \`.Swap()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.Swap) - \`.ForEach()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.ForEach) - \`.Match()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.Match) - \`.MapLeft()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.MapLeft) - \`.MapRight()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either.MapRight) Other: - \`mo.Fold[T, U, R any](f Foldable[T, U], successFunc func(U) R, failureFunc func(T) R) R\` [doc](https://pkg.go.dev/github.com/samber/mo#Fold) Sub-package \`either\` (transformations and pipes): - \`either.MapLeft()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either#MapLeft) - \`either.MapRight()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either#MapRight) - \`either.Match()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either#Match) - \`either.Swap()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either#Swap) - \`either.Pipe1..Pipe10()\` [docs](https://pkg.go.dev/github.com/samber/mo/either#Pipe1) ### EitherX[T1, ..., TX] (With X between 3 and 5) \`EitherX\` respresents a value of X possible types. For example, an \`Either3\` value is either \`T1\`, \`T2\` or \`T3\`. Constructors: - \`mo.NewEitherXArgY()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewEither5Arg1). 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](https://pkg.go.dev/github.com/samber/mo#Either5.IsArg1) - \`.ArgX()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.Arg1) - \`.MustArgX()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.MustArg1) - \`.Unpack()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.Unpack) - \`.ArgXOrElse()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.Arg1OrElse) - \`.ArgXOrEmpty()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.Arg1OrEmpty) - \`.ForEach()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.ForEach) - \`.Match()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.Match) - \`.MapArgX()\` [doc](https://pkg.go.dev/github.com/samber/mo#Either5.MapArg1) Sub-packages \`either3\`, \`either4\`, \`either5\` (transformations and pipes): - either3 docs: https://pkg.go.dev/github.com/samber/mo/either3 - \`either3.Match()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either3#Match) - \`either3.MapArg1()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either3#MapArg1) - \`either3.MapArg2()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either3#MapArg2) - \`either3.MapArg3()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either3#MapArg3) - \`either3.Pipe1..Pipe10()\` [docs](https://pkg.go.dev/github.com/samber/mo/either3#Pipe1) - either4 docs: https://pkg.go.dev/github.com/samber/mo/either4 - \`either4.Match()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either4#Match) - \`either4.MapArg1()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either4#MapArg1) - \`either4.MapArg2()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either4#MapArg2) - \`either4.MapArg3()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either4#MapArg3) - \`either4.Pipe1..Pipe10()\` [docs](https://pkg.go.dev/github.com/samber/mo/either4#Pipe1) - either5 docs: https://pkg.go.dev/github.com/samber/mo/either5 - \`either5.Match()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either5#Match) - \`either5.MapArg1()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either5#MapArg1) - \`either5.MapArg2()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either5#MapArg2) - \`either5.MapArg3()()\` [doc](https://pkg.go.dev/github.com/samber/mo/either5#MapArg3) - \`either5.Pipe1..Pipe10()\` [docs](https://pkg.go.dev/github.com/samber/mo/either5#Pipe1) ### 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](https://pkg.go.dev/github.com/samber/mo#NewFuture) Methods: - \`.Then()\` [doc](https://pkg.go.dev/github.com/samber/mo#Future.Then) - \`.Catch()\` [doc](https://pkg.go.dev/github.com/samber/mo#Future.Catch) - \`.Finally()\` [doc](https://pkg.go.dev/github.com/samber/mo#Future.Finally) - \`.Collect()\` [doc](https://pkg.go.dev/github.com/samber/mo#Future.Collect) - \`.Result()\` [doc](https://pkg.go.dev/github.com/samber/mo#Future.Result) - \`.Cancel()\` [doc](https://pkg.go.dev/github.com/samber/mo#Future.Cancel) ### 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: - \`mo.NewIO()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIO) - \`mo.NewIO1()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIO1) - \`mo.NewIO2()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIO2) - \`mo.NewIO3()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIO3) - \`mo.NewIO4()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIO4) - \`mo.NewIO5()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIO5) Methods: - \`.Run()\` [doc](https://pkg.go.dev/github.com/samber/mo#Future.Run) ### 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](https://pkg.go.dev/github.com/samber/mo#NewIOEither) - \`mo.NewIOEither1()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIOEither1) - \`mo.NewIOEither2()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIOEither2) - \`mo.NewIOEither3()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIOEither3) - \`mo.NewIOEither4()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIOEither4) - \`mo.NewIOEither5()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewIOEither5) Methods: - \`.Run()\` [doc](https://pkg.go.dev/github.com/samber/mo#IOEither.Run) ### 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](https://pkg.go.dev/github.com/samber/mo#NewTask) - \`mo.NewTask1()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTask1) - \`mo.NewTask2()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTask2) - \`mo.NewTask3()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTask3) - \`mo.NewTask4()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTask4) - \`mo.NewTask5()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTask5) - \`mo.NewTaskFromIO()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskFromIO) - \`mo.NewTaskFromIO1()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskFromIO1) - \`mo.NewTaskFromIO2()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskFromIO2) - \`mo.NewTaskFromIO3()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskFromIO3) - \`mo.NewTaskFromIO4()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskFromIO4) - \`mo.NewTaskFromIO5()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskFromIO5) Methods: - \`.Run()\` [doc](https://pkg.go.dev/github.com/samber/mo#Task.Run) ### 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: - \`mo.NewTaskEither()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskEither) - \`mo.NewTaskEitherFromIOEither()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewTaskEitherFromIOEither) Methods: - \`.Run()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.Run) - \`.OrElse()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.OrElse) - \`.Match()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.Match) - \`.TryCatch()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.TryCatch) - \`.ToTask()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.ToTask) - \`.ToEither()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.ToEither) ### State[S any, A any] \`State\` represents a function \`(S) -> (A, S)\`, where \`S\` is state, \`A\` is result. Constructors: - \`mo.NewState()\` [doc](https://pkg.go.dev/github.com/samber/mo#NewState) - \`mo.ReturnState()\` [doc](https://pkg.go.dev/github.com/samber/mo#ReturnState) Methods: - \`.Run()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.Run) - \`.Get()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.Get) - \`.Modify()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.Modify) - \`.Put()\` [doc](https://pkg.go.dev/github.com/samber/mo#TaskEither.Put) ### Foldable[T, U] 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) R\` [doc](https://pkg.go.dev/github.com/samber/mo#Fold) ## Benchmark // @TODO This library does not use \`reflect\` package. We don't expect overhead. ## Contributing - Ping me on Twitter [@samuelberthe](https://twitter.com/samuelberthe) (DMs, mentions, whatever :)) - Fork the [project](https://github.com/samber/mo) - Fix [open issues](https://github.com/samber/mo/issues) or request new features Don't hesitate ;) \`\`\`bash # Install some dev dependencies make tools # Run tests make test # or make watch-test \`\`\` ## Contributors  ## Show your support Give a ⭐️ if this project helped you! [](https://github.com/sponsors/samber) ## License Copyright © 2022 [Samuel Berthe](https://github.com/samber). This project is [MIT](./LICENSE) licensed.