IndexMap doesn't implement `Hash`

[victorteokw]

Hi,

Thanks for this great package. When I use some type which contains IndexMap as keys to some other map, I get this error message. Could this be implemented or this is by design?

Thanks

[cuviper]

It is by design, because its Eq is based on containing equivalent items regardless of order, like HashMap, and Hash has to be consistent with Eq if they're both implemented. But this comes up often: #67, #75, #155, and a bit of #153.

The indexmap::map::Slice type does implement order-sensitive Eq and Hash, so you could possibly use a wrapper for your keys that forwards to the map .as_slice() for those operations.