There's nothing stopping you writing your own hash map that can be configured with a custom hash function. The builtin map is limited to types for which the la

There's nothing stopping you writing your own hash map that can be configured with a custom hash function. The builtin map is limited to types for which the language defines ==. It's a simplifying trade-off; I don't think "acceptable" versus "unacceptable" enters into it. One could imagine expanding the builtin map type to support a hash function, and that was something that was considered early on, but it added complexity that just wasn't needed most of the time.