I tried my hand at it for fun :) it is a linear probed hashmap based on
uint64 map keys: https://gotipplay.golang.org/p/gzrbS-B6ixg
I claim no rights nor responsibility for the above example; it only took me
like 20 minutes and has extremely minimal testing; it may contain bugs. Use
at your own risk. Et cetera et cetera I am not a lawyer ;)
On Thursday, December 23, 2021 at 5:03:53 PM UTC-7 Ian Lance Taylor wrote:
> On Thu, Dec 23, 2021 at 12:42 PM aind...@gmail.com <aind...@gmail.com>
> wrote:
> >
> > Now that generics is coming along, is there an easy way to extend the
> builtin map type to use a non-comparable key type? For example, given this
> constraint
> >
> > type Key[T any] interface {
> > Size() uint64
> > Hash(seed uint64) uint64
> > Equal(T) bool
> > }
> >
> > and a type Foo like
> >
> > type Foo []int
> > func (a Foo) Size() uint64 { ... }
> > func (a Foo) Hash(seed uint64) uint64 { ... }
> > func (a Foo) Equal(b Foo) bool { ... }
> >
> > I'd like a map[Foo]struct{}. Is this possible now? Or does the runtime
> map have to be updated to support this?
>
> The addition of generics is independent of whether the builtin map
> type can support non-comparable key types.
>
> With generics it now becomes possible to write a new map type with
> explicitly specified hash and equality functions. This could work
> much like the builtin map type, but it would have methods (e.g.,
> Lookup, Insert) rather than special syntax. However, nobody has
> written such a type yet as far as I know.
>
> Note that if anybody wants to write such a type, I recommend passing
> in comparison and equality functions rather than requiring the key
> type to have methods, as I mentioned in the talk at
> https://www.youtube.com/watch?v=Pa_e9EeCdy8 .
>
> Ian
>
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