Hi,
Say i want to implement a “map” function on generic slices with go1.18beta1… The method’s prototype should be something like:
func (xs List[T]) Map(fct func(x T) S) List[S] {...} assuming List[T] is defined as:
type List[T any] []T
Unfortunately, i’ve no found how to introduce the S generic in the method declaration. Is it even possible?
I am not familiar with generics in Go, but I’ve seen this specific question about wanting a Map function all over Reddit and it’s my understanding that you cannot do this because only top-level functions can have multiple generic parameters.
Ok, thanks for the tip…
@jaco If you drop the requirement for defining a custom slice type, the map works well:
func Map[T, S any](t []T, fct func(x T) S) []S {
var s []S
for _, x := range t {
s = append(s, fct(x))
}
return s
}
func main() {
t := []int{1, 2, 3}
s := Map(t, func(n int) int64 {
return int64(n)
})
fmt.Println(s)
}
The point is, the built-in slice type is generic already, thus a custom generic slice type might not be necessary (unless it is needed for some other reason).
Yes, that’s what I’ll do… I preferred to have a dotted notation to simplify the call sequence, but never mind…
I find xs.map(fct).filter(pred) clearer than filter(map(xs, fct), pred)… But i can live with it…
Agreed, nested functions are harder to read than chained ones, but OTOH, code using custom generic slice types is (usually) also harder to read than code using standard slices.