# README
fp-go
Fp-go is a collection of Functional Programming helpers powered by Golang 1.18+ generics.
Inspired by
Contents
Install
Requires go 1.18+
go get github.com/repeale/fp-go
Features
Currying
By default! Data last!
func isPositive(x int) bool {
return x > 0
}
func main() {
filterPositive := fp.Filter(isPositive)
numbers := []int{1, 2, 3, 4, 5}
positives := filterPositive(numbers)
}
Variations
Variations allows you to get different parameters in the callback function so that you get only only what is really needed.
Default
Only the current item is available:
fp.Map[int, string](func(x int) { ... })
WithIndex
Current element and index are available:
fp.MapWithIndex[int, string](func(x int, i int) { ... })
WithSlice
Current element, index and the whole slice are available:
fp.MapWithSlice[int, string](func(x int, i int, xs: []int) { ... })
Helpers
Every
Determines whether all the members of an array satisfy the specified test.
Variations EveryWithIndex and EveryWithSlice
fp.Every(func(x int) bool { return x > 0 })([]int{1, 2, 3})
// => true
Filter
Returns the elements of an array that meet the condition specified in a callback function.
Variations FilterWithIndex and FilterWithSlice
fp.Filter(func(x int) bool { return x > 0 })([]int{-1, 2, -3, 4})
// => []int{2, 4}
Flat
Returns a new array with all sub-array elements concatenated into it.
fp.Flat([][]int{{1, 2}, {3, 4}})
// => []int{1, 2, 3, 4}
FlatMap
Calls a defined callback function on each element of an array. Then, flattens the result into a new array. This is identical to a map followed by flat.
Variations FlatMapWithIndex and FlatMapWithSlice
fp.FlatMap(func(x int) []int { return []int{x, x} })([]int{1, 2})
// => []int{1, 1, 2, 2}
Map
Calls a defined callback function on each element of an array, and returns an array that contains the results.
Variations MapWithIndex and MapWithSlice
fp.Map(func(x int64) string {
return strconv.FormatInt(x, 10)
})([]int64{1, 2, 3})
// => []string{"1", "2", "3", "4"}
Reduce
Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
Variations ReduceWithIndex and ReduceWithSlice
fp.Reduce(func(acc int, curr int) int { return acc + curr }, 0)([]int{1, 2, 3})
// => 6
Some
Determines whether the specified callback function returns true for any element of an array.
Variations SomeWithIndex and SomeWithSlice
fp.Some(func(x int) bool { return x < 0 })([]int{1, 2, 3})
// => false
Compose
Performs right-to-left function composition.
Variations Compose2 to Compose16 stating the number of functions you are going to compose.
func isPositive(x int) bool {
return x > 0
}
func sumTwo(x int) int {
return x + 2
}
Compose2(fp.Filter(isPositive), fp.Map(sumTwo))([]int{1, 2, 3, -1})
// => []int{3,4,5,1}
Pipe
Performs left-to-right function composition.
Variations Pipe2 to Pipe16 stating the number of functions you are going to compose.
func isPositive(x int) bool {
return x > 0
}
func sumTwo(x int) int {
return x + 2
}
Pipe2(fp.Filter(isPositive), fp.Map(sumTwo))([]int{1, 2, 3, -1})
// => []int{3,4,5}
Curry
Allow to transfrom a function that receives a certain amount of params in single functions that take one single param each.
Variations Curry2 to Curry16 stating the number of params will be curried individually.
curryedSum := Curry2(func(a int, b int) int { return a + b })
curryedSum(1)(2)
Structs
Option
Option represents encapsulation of an optional value, it might be used as the return type of functions which may or may not return a meaningful value when they are applied.
Option exports Some, None, IsSome, IsNone, Chain, Exists, Flatten, FromError, FromErrorFn, FromPredicate, GetOrElse, Map, Match.
Either
Either represent a value that can have two possible types. It is common to see Either used to represent a success value Right or a failure value Left, although that doesn't have to be the case.
An instance of Either is either an instance of Left or Right.
Either exports Left, Right, IsLeft, IsRight, Exists, Flatten, FromError, FromErrorFn, FromOption, FromPredicate, GetOrElse, Map, MapLeft, Match,