On Fri, Feb 11, 2022 at 12:51 PM Kamil Ziemian <kziemian...@gmail.com> wrote:
> I'm now trying to play with compilers with this construction. > > type someDifferentInt[float64] int > In Go 1.17 I get this complain > > invalid array bound float64 > > type float64 is not an expression > while in Go 1.18beta2 I get > > float64 (type) is not an expression > It probably need be this way, that with using "[T Constraint]" to define > (?) type parameters, compiler can't says that it is "invalid array bound > float64", but new error message is still less useful. I guess we need to > live with that. > I can't see why the parser can't see that this should (if anything) be interpreted as an array type declaration. To me, this seems like a regression. I'd suggest maybe filing an issue. > > type someOtherInt[float64 float64] int > This is awful thing to write, but I still perplexed by what compilers say. > Go 1.17: > > syntax error: unexpected float64, expecting ] > Go 1.18beta2: > > cannot use a type parameter as constraint > This error message seems reasonably clear to me. You are declaring a type parameter `float64` with constraint `float64`. It tells you that you can't use type parameters as constraints. > > This example is to compare Go compilers with and without generics. > > type someAnotherInt[T any] int > Go 1.17: > > syntax error: unexpected any, expecting ] > > Go 1.18beta2: it compile just fine. Can someone explain me, why compiler > can't throw an error when it find unused type parameter? I like that in Go > unused variable, or import, is compile time error and I would appreciate > the same behavior with unused type parameters. > > I need to go for a while, I will go back with more questions about what > you can get when using "[]" in Go. > > Best, > Kamil > > -- > 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/b085b991-e59e-4225-a4d6-36b2391e1dc2n%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/b085b991-e59e-4225-a4d6-36b2391e1dc2n%40googlegroups.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/CAEkBMfFET%3DRVRq6%2BtAtG4Xi0%2BhUMOxxwi1qAH8GHFdzc%3DzTLyw%40mail.gmail.com.
