[kitd]

I find the opposite effect to be true. In many/most cases, the type model of a piece of Go code is not at all obvious without detailed inspection.

When pretty much anything can implement any interface, and one can only tell whether an interface is fully implemented by close examination of a whole source file (rather than reading a simple implements keyword), the cognitive load is far greater.

[kjeetgill]

I understand where you're coming from, and I've made many a shallow criticism from a place of frustration, but please understand that thats what this is.

The lack of an implements is not just a matter of "less syntax fever!" but one that facilitates other language design choices: in particular static compile time duck-typing. Among the "everybody knows or knows-about" class of languages this is pretty fresh. You can go back and forth on the point of this (or the value of the trade-offs) but it's pretty key to Go's flavor. As a Java geek, I'm pretty familiar with the way you'd prefer and I like it quite a bit too, but once I'd tried it, I've really missed Go's flavor more than a handful of times.

Static duck-typing has some great downstream ecosystem effects. For one, it really facilitates smaller, tight interfaces. If my code uses a type A from another package B, and A has 20 functions that in my code only uses 3 of, I can create an interface on my end with just the 3. Then any testing or any alternative implementations apply only to the minimal interface. If that alternative implementation is by another author, it can interop with my code without importing type A package B. Obviously you don't need this all the time but it's killer when you do.

[Elrac]

No doubt our different perspectives are a result of us doing different things with Go.

I don't write compilers or other "highbrow" Computer Science-heavy programs. I most frequently find myself writing interface software, data converters, text extractors, near-system utilities. Lots of the kind of things some people might write in C or Perl. As a result, my usage of data types, even structs, is pretty light. Turns out I can do most of my work with the built-in types: integers, characters, strings, arrays and hashes. I rarely even need/use interfaces!

Data types don't play a big role in my work. Your mileage may vary, obviously.