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Silly Go–with–generics (FGG) program to demonstrate the syntax.
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| package main | |
| import "fmt" | |
| func Fold(type T, U)(acc T, f func(T, U) T, xs []U) T { | |
| for _, x := range xs { | |
| acc = f(acc, x) | |
| } | |
| return acc | |
| } | |
| func Map(type T, U)(xs []T, f func(T) U) []U { | |
| ys := make([]U, 0, len(xs)) | |
| ys = Fold(ys, func(acc []U, x T) []U { return append(acc, f(x)) }, xs) | |
| return ys | |
| } | |
| func Filter(type T)(xs []T, f func(T) bool) []T { | |
| ys := make([]T, 0, len(xs)) | |
| ys = Fold( | |
| ys, | |
| func(acc []T, x T) []T { if f(x) { return append(acc, x) } else { return acc } }, | |
| xs, | |
| ) | |
| if len(ys) != len(xs) { | |
| ys = ys[:len(ys):len(ys)] | |
| } | |
| return ys | |
| } | |
| func main() { | |
| incremented := Map([]int{1,2,3}, func(x int) int { return x + 1}) | |
| filtered := Filter(incremented, func(x int) bool { return x % 2 == 0 }) | |
| summed := Fold(0, func(acc int, x int) int { return acc + x }, filtered) | |
| fmt.Println(incremented, filtered, summed) | |
| } |
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