I think in real usage (in my experience), this is very rarely the case. The only thing Generics are really extremely useful for is writing data structures that you can re-use with multiple data types.
Also, I tend to appreciate Go's approach of writing more code in these situations, because in general the code is still far more readable than a C++ Template (for example).
The Go creators have not ruled out adding Generics, they are simply being very careful about how they implement it. I would rather have this situation than something like a generic Java/C#/C++ style generics implementation rammed in because it is demanded by people who have hardly touched the language (or refuse to touch it until said feature is added).
"I think in real usage (in my experience), this is very rarely the case. The only thing Generics are really extremely useful for is writing data structures that you can re-use with multiple data types"
When working in .NET on framework-y code I use generics with reflection a lot because it makes it easy to remove a whole swathe of repetitive code. Mapping from one object to another using a Mapper<TFrom, TTo> with generic constraints, reflection and some over-ridable conventions springs to mind.
Not an argument for adding generics in Go, or against Go itself as I haven't yet found the time to play with it. However I do think generics can be more useful than people give them credit for.
The thing is that Go has generics already for the most common data types: slices (vectors, what Python calls 'lists', others call them 'arrays'), channels (iterators, generators), and maps (dictionaries, hashes). Since there's already a built-in map[T1] T2, so you wouldn't need to build it yourself, which saves even more work.
If what it has are a handful of special cases baked into the language, saying the language supports it is probably overselling (similarly, having types like `float[3]' doesn't mean we consider C as supporting dependent types).
"The only thing Generics are really extremely useful for is writing data structures that you can re-use with multiple data types." Take a look at C++'s STL: a large set of generic algorithms that work with any data structure (built-in or user-written) supporting the standard iterator protocols. Many people think of STL as "a bunch of container classes", and ignore the algorithms.
Also, I tend to appreciate Go's approach of writing more code in these situations, because in general the code is still far more readable than a C++ Template (for example).
The Go creators have not ruled out adding Generics, they are simply being very careful about how they implement it. I would rather have this situation than something like a generic Java/C#/C++ style generics implementation rammed in because it is demanded by people who have hardly touched the language (or refuse to touch it until said feature is added).