On: Class Hierarchies? Don't Do That

[gsg]

> Of course, it's also more limited in how it interacts with the corresponding values.

This is backwards. Polymorphic values without constraints admit almost no operations at all - you can "copy" them, that's it. This is true to the point that (save diverging) given f :: a -> a, f can only have one meaning.

Invariance of sequence elements is also far less problematic in ML-family languages because they have sums.

[dllthomas → gsg]

"It" here being the fully polymorphic version. Rereading, it does seem misleading (or at best ambiguous) so I've expanded the pronoun.

[gsg → dllthomas]

I see. Sorry, I should have interpreted that more generously.

[dllthomas → gsg]

You're forgiven - certainly calling out the lack of clarity was important!