Monad, Functional Programming features for Golang
For Generics version(>=go1.18):generics
go get github.com/TeaEntityLab/fpGo/v2For NonGenerics version(<=go1.17):non-generics
go get github.com/TeaEntityLab/fpGoI love functional programing, Rx-style coding, and Optional usages.
However it's hard to implement them in Golang, and there're few libraries to achieve parts of them.
Thus I implemented fpGo. I hope you would like it :)
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Optional/Maybe
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Monad, Rx-like
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Publisher
-
Pattern matching
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Fp functions
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Java8Stream-like Collection
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Queue (LinkedListQueue/ChannelQueue/BufferedChannelQueue/ConcurrentQueue)
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PythonicGenerator-like Coroutine(yield/yieldFrom)
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Akka/Erlang-like Actor model(send/receive/spawn/states)
-
network/SimpleHTTP inspired by Retrofit
-
worker/WorkerPool inspired by JavaExecutorService & goroutine pool libs
- fp functions(Dedupe/Difference/Distinct/IsDistinct/DropEq/Drop/DropLast/DropWhile/IsEqual/IsEqualMap/Every/Exists/Intersection/Keys/Values/Max/Min/MinMax/Merge/IsNeg/IsPos/PMap/Range/Reverse/Set/Some/IsSubset/IsSuperset/Take/TakeLast/Union/IsZero/Zip/GroupBy/UniqBy/Flatten/Prepend/Partition/Tail/Head/SplitEvery)
var m MaybeDef[interface{}]
var orVal int
var boolVal bool
// IsPresent(), IsNil()
m = Maybe.Just(1)
boolVal = m.IsPresent() // true
boolVal = m.IsNil() // false
m = Maybe.Just(nil)
boolVal = m.IsPresent() // false
boolVal = m.IsNil() // true
// Or()
m = Maybe.Just(1)
fmt.Println((m.Or(3))) // 1
m = Maybe.Just(nil)
fmt.Println((m.Or(3))) // 3
// Let()
var letVal int
letVal = 1
m = Maybe.Just(1)
m.Let(func() {
letVal = 2
})
fmt.Println(letVal) // letVal would be 2
letVal = 1
m = Maybe.Just(nil)
m.Let(func() {
letVal = 3
})
fmt.Println(letVal) // letVal would be still 1Example:
var m *MonadIODef[interface{}]
var actualInt int
m = MonadIO.Just(1)
actualInt = 0
m.Subscribe(Subscription[interface{}]{
OnNext: func(in interface{}) {
actualInt, _ = Maybe.Just(in).ToInt()
},
})
fmt.Println(actualInt) // actualInt would be 1
m = MonadIO.Just(1).FlatMap(func(in interface{}) *MonadIODef[interface{}] {
v, _ := Maybe.Just(in).ToInt()
return MonadIO.Just(v + 1)
})
actualInt = 0
m.Subscribe(Subscription[interface{}]{
OnNext: func(in interface{}) {
actualInt, _ = Maybe.Just(in).ToInt()
},
})
fmt.Println(actualInt) // actualInt would be 2Example(Generics):
var s *StreamDef[int]
var tempString = ""
s = StreamFromArray([]int{}).Append(1, 1).Extend(StreamFromArray([]int{2, 3, 4}))
tempString = ""
for _, v := range s.ToArray() {
tempString += Maybe.Just(v).ToMaybe().ToString()
}
fmt.Println(tempString) // tempString would be "11234"
s = s.Distinct()
tempString = ""
for _, v := range s.ToArray() {
tempString += Maybe.Just(v).ToMaybe().ToString()
}
fmt.Println(tempString) // tempString would be "1234"Example(Non-Generics/interface{}):
var s *StreamForInterfaceDef
var tempString string
s = StreamForInterface.FromArrayInt([]int{}).Append(1, 1).Extend(StreamForInterface.FromArrayInt([]int{2, 3, 4})).Extend(StreamForInterface.FromArray([]interface{}{nil})).Extend(nil)
tempString = ""
for _, v := range s.ToArray() {
tempString += Maybe.Just(v).ToMaybe().ToString()
}
fmt.Println(tempString) // tempString would be "11234<nil>"
s = s.Distinct()
tempString = ""
for _, v := range s.ToArray() {
tempString += Maybe.Just(v).ToMaybe().ToString()
}
fmt.Println(tempString) // tempString would be "1234<nil>"
s = s.FilterNotNil()
tempString = ""
for _, v := range s.ToArray() {
tempString += Maybe.Just(v).ToMaybe().ToString()
}
fmt.Println(tempString) // tempString would be "1234"Queue(LinkedListQueue/ChannelQueue/BufferedChannelQueue/ConcurrentQueue) (inspired by Collection libs)
Example:
var queue Queue[int]
var stack Stack[int]
var err error
var result int
linkedListQueue := NewLinkedListQueue[int]()
queue = linkedListQueue
stack = linkedListQueue
concurrentQueue := NewConcurrentQueue[int](queue)
// As a Queue, Put(val) in the TAIL and Take() in the HEAD
err = queue.Offer(1)
err = queue.Offer(2)
err = queue.Offer(3)
result, err = queue.Poll() // Result should be 1
result, err = queue.Poll() // Result should be 2
result, err = queue.Poll() // Result should be 3
result, err = queue.Poll() // Err: ErrQueueIsEmpty
// As a Stack, Push(val) & Pop() in the TAIL.
err = stack.Push(1)
err = stack.Push(2)
err = stack.Push(3)
result, err = stack.Pop() // Result should be 3
result, err = stack.Pop() // Result should be 2
result, err = stack.Pop() // Result should be 1
result, err = stack.Pop() // Err: ErrStackIsEmptyExample:
var err error
var result int
var timeout time.Duration
bufferedChannelQueue := NewBufferedChannelQueue[int](3, 10000, 100).
SetLoadFromPoolDuration(time.Millisecond / 10).
SetFreeNodeHookPoolIntervalDuration(1 * time.Millisecond)
err = queue.Offer(1)
err = queue.Offer(2)
err = queue.Offer(3)
timeout = 1 * time.Millisecond
result, err = bufferedChannelQueue.TakeWithTimeout(timeout) // Result should be 1
result, err = bufferedChannelQueue.TakeWithTimeout(timeout) // Result should be 2
result, err = bufferedChannelQueue.TakeWithTimeout(timeout) // Result should be 3Example:
actual := 0
// Channel for results
resultChannel := make(chan interface{}, 1)
// Message CMDs
cmdSpawn := "spawn"
cmdShutdown := "shutdown"
// Testee
actorRoot := Actor.New(func(self *ActorDef[interface{}], input interface{}) {
// SPAWN: for ROOT
if input == cmdSpawn {
self.Spawn(func(self *ActorDef[interface{}], input interface{}) {
// SHUTDOWN: for Children
if input == cmdShutdown {
self.Close()
return
}
// INT cases: Children
val, _ := Maybe.Just(input).ToInt()
resultChannel <- val * 10
})
return
}
// SHUTDOWN: for ROOT
if input == cmdShutdown {
for _, child := range self.children {
child.Send(cmdShutdown)
}
self.Close()
close(resultChannel)
return
}
// INT cases: ROOT
intVal, _ := Maybe.Just(input).ToInt()
if intVal > 0 {
for _, child := range self.children {
child.Send(intVal)
}
}
})
// Sequential Send messages(async)
go func() {
actorRoot.Send(cmdSpawn)
actorRoot.Send(10)
actorRoot.Send(cmdSpawn)
actorRoot.Send(20)
actorRoot.Send(cmdSpawn)
actorRoot.Send(30)
}()
i := 0
for val := range resultChannel {
intVal, _ := Maybe.Just(val).ToInt()
actual += intVal
i++
if i == 5 {
go actorRoot.Send(cmdShutdown)
}
}
// Result would be 1400 (=10*10+20*10+20*10+30*10+30*10+30*10)
fmt.Println(actual)actorRoot := Actor.New(func(self *ActorDef[interface{}], input interface{}) {
// Ask cases: ROOT
switch val := input.(type) {
case *AskDef[interface{}, int]:
intVal, _ := Maybe.Just(val.Message).ToInt()
// NOTE If negative, hanging for testing Ask.timeout
if intVal < 0 {
break
}
val.Reply(intVal * 10)
break
}
})
// var timer *time.Timer
var timeout time.Duration
timeout = 10 * time.Millisecond
// Normal cases
// Result would be 10
actual = AskNewGenerics[interface{}, int](1).AskOnce(actorRoot)
// Ask with Timeout
// Result would be 20
actual, _ = AskNewGenerics[interface{}, int](2).AskOnceWithTimeout(actorRoot, timeout)
// Ask channel
// Result would be 30
ch := AskNewGenerics[interface{}, int](3).AskChannel(actorRoot)
actual = <- ch
close(ch)
// Timeout cases
// Result would be 0 (zero value, timeout)
actual, err = AskNewGenerics[interface{}, int](-1).AskOnceWithTimeout(actorRoot, timeout)Example:
var fn01 = func(args ...int) []int {
val := args[0]
return SliceOf(val + 1)
}
var fn02 = func(args ...int) []int {
val := args[0]
return SliceOf(val + 2)
}
var fn03 = func(args ...int) []int {
val := args[0]
return SliceOf(val + 3)
}
// Result would be 6
result := Compose(fn01, fn02, fn03)((0))[0]