(fun)ctional go

First class/Pure functions

Higher Order Functions

Immutability(kinda)

Currying

First class functions?type Fi func() int

func doThing(s string, i int, fun Fi) { fmt.Println(s) // ohai fmt.Println(i) // 42 fmt.Println(fun) // pointer e.g. 0x2200 fmt.Println(fun()) // 1}

func main() { doThing("ohai", 42, func () int { return 1 })}

Higher order functions?

Return other functionstype Fi func(int) int

func makeAdder(x int) Fi { return func (y int) int { return x + y }}

func main() { add2 := makeAdder(2) fmt.Println(add2(1)) // 3 fmt.Println(add2(2)) // 4}

Take functions as argumentstype Fi func(int) inttype Fii func(int, int) int

func MakeFi(x int, fun Fii) Fi { return func (y int) int { return fun(x, y) }}

func main() { even := MakeFi(2, func (x, y int) int { return x % y }) fmt.Println(even(1)) // 0 fmt.Println(even(4)) // 2}

Pure Functions?Idempotent, stateless and without side effect

// not pure external := 1

func bad(i int) int { external = i + external // side effect and state full return external}

fmt.Println(bad(external)) // 2fmt.Println(bad(external)) // 4 not idempotent

// pureexternal := 1

func good(x int) int { // only uses variables in closure // no side effects no state return x + 1}

fmt.Println(good(external)) // 2fmt.Println(good(external)) // 2 idempotent

Immutability

An immutable object is an object whose state cannot be modified after it is created.

Currying Is the technique of transforming a function that takes multiple arguments in such a way that it

can be called as a chain.

func makeAdd(a int) func(int) int { return func(b int) int { return a + b }}

func main() { add2 := makeAdd(2) add3 := makeAdd(3) fmt.Println(add2(5), add3(6))}

func modulo(x, y int) int { return x % y}

func makeModulo(x int) func(int) int { return func(y int) int { return modulo(x, y) }}

func main() { isOdd := makeModulo(2) fmt.Println(isOdd(2)) // 0 fmt.Println(isOdd(3)) // 2}

How about something useful?

Thank you!Chirstan Johansen, Brian Lonsdorf and Everyone at

UBXD