FWIW I also came across this issue recently in a different context and similarly wondered if a nillable constraint might be a good idea.
There is a kinda workaround although you won't like it :) https://go2goplay.golang.org/p/-nDAUVYWuxo On Tue, 23 Jun 2020 at 05:43, 'Bryan C. Mills' via golang-nuts < golang-nuts@googlegroups.com> wrote: > I tried writing a generic “FirstNonNil” function, but got stuck at the "== > nil" part. > > First I thought to maybe add a type list enumerating all of the nillable > types, but I don't have a way to enumerate all of the possible interface > types as part of that list, and there is no constraint for “any interface > type”. > > Then I thought I could use a `var zero T` variable and compare `== zero` > instead of `== nil`. But that doesn't work either: I need the `comparable` > constraint to get `==`, but not every nillable type is comparable with an > arbitrary variable (slices, maps, and functions are not). > > So it seems that the best I can do is to write a generic `First` function > and make the caller write out `func (x T) bool { return x != nil }` > explicitly at every call site. Did I miss a better option? > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CAKWVi_SED7FvqerjhzX8OBss3MHzbb3aw%2BLOcRcC3Lf3GUZCfw%40mail.gmail.com > <https://groups.google.com/d/msgid/golang-nuts/CAKWVi_SED7FvqerjhzX8OBss3MHzbb3aw%2BLOcRcC3Lf3GUZCfw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAJhgacirMen54vZw7SnUHvM2DtADm9fnjF3dMziATnC4WvcmaQ%40mail.gmail.com.
