This is actually a really good question. To the spec-mobile! https://golang.org/ref/spec#Calls
Except for one special case, arguments must be single-valued expressions > assignable to the parameter types of F and are evaluated before the > function is called. Okay, so the arguments must be assignable. That must then mean that a value of type TI is not assignable to a type int. https://golang.org/ref/spec#Assignability A value x is *assignable* to a variable > <https://golang.org/ref/spec#Variables> of type T ("x is assignable to T") > in any of these cases: > > - x's type is identical to T. > > > - x's type V and T have identical underlying types > <https://golang.org/ref/spec#Types> and at least one of V or T is not > a named type <https://golang.org/ref/spec#Types>. > > > - … > > The second bullet point is the important one: Both V (TI) and T (int) have the same underlying type (namely int), but both are named types (with int being a predeclared identifier). Now, if you contrast that with the slice-case, here []int is *not* a named type, but a type-literal. That means, for []int and TIS, this second bullet point will evaluate to true, as one of the two is not a named type, so a TIS is assignable to an []int. Personally, I think this is somewhat confusing (though it is in line with the spec). On Sat, Jul 16, 2016 at 10:15 PM, T L <tapir....@gmail.com> wrote: > > package main >> >> func fi(i int) {} >> func fis(is []int) {} >> >> type TI int >> type TIS []int >> >> func main() { >> var ti TI >> fi(ti) // cannot use ti (type TI) as type int in argument to fi >> >> var tis TIS >> fis(tis) // no problems! >> } >> >> -- > 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. > For more options, visit https://groups.google.com/d/optout. > -- 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. For more options, visit https://groups.google.com/d/optout.
