fpGo
Monad, Functional Programming features for Golang
Why
I 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 :)
Features
-
Optional/Maybe
-
Monad, Rx-like
-
Publisher
-
Pattern matching
-
Fp functions
-
Java8Stream-like Collection
-
PythonicGenerator-like Coroutine(yield/yieldFrom)
Usage
Optional (IsPresent/IsNil, Or, Let)
var m MaybeDef
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 1MonadIO (RxObserver-like)
Example:
var m *MonadIODef
var actualInt int
m = MonadIO.Just(1)
actualInt = 0
m.Subscribe(Subscription{
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 {
v, _ := Maybe.Just(in).ToInt()
return MonadIO.Just(v + 1)
})
actualInt = 0
m.Subscribe(Subscription{
OnNext: func(in interface{}) {
actualInt, _ = Maybe.Just(in).ToInt()
},
})
fmt.Println(actualInt) // actualInt would be 2Stream (inspired by Collection libs)
Example:
var s *StreamDef
var tempString = ""
s = Stream.FromArrayInt([]int{}).Append(1).Extend(Stream.FromArrayInt([]int{2, 3, 4})).Extend(Stream.FromArray([]interface{}{nil}))
tempString = ""
for _, v := range s.ToArray() {
tempString += Maybe.Just(v).ToMaybe().ToString()
}
fmt.Println(tempString) // tempString would be "1234<nil>"
s = s.Distinct()
tempString = ""
for _, v := range s.ToArray() {
tempString += Maybe.Just(v).ToMaybe().ToString()
}
fmt.Println(tempString) // tempString would be "1234"Compose
Example:
var fn01 = func(args ...interface{}) []interface{} {
val, _ := Maybe.Just(args[0]).ToInt()
return SliceOf(val + 1)
}
var fn02 = func(args ...interface{}) []interface{} {
val, _ := Maybe.Just(args[0]).ToInt()
return SliceOf(val + 2)
}
var fn03 = func(args ...interface{}) []interface{} {
val, _ := Maybe.Just(args[0]).ToInt()
return SliceOf(val + 3)
}
// Result would be 6
result := Compose(fn01, fn02, fn03)((0))[0]