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A comment on Class Hierarchies? Don't Do That. Parent comment

Re:Class Hierarchies? Don't Do That by gsg on Sunday March 30, 2014 @03:33PM (#7497542)
> 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.

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Re:Class Hierarchies? Don't Do That by dllthomas on Sunday March 30, 2014 @03:46PM (#7497603)
"It" here being the fully polymorphic version. Rereading, it does seem misleading (or at best ambiguous) so I've expanded the pronoun.
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Re:Class Hierarchies? Don't Do That by gsg on Sunday March 30, 2014 @04:06PM (#7497692)
I see. Sorry, I should have interpreted that more generously.
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Re:Class Hierarchies? Don't Do That by dllthomas on Sunday March 30, 2014 @04:31PM (#7497785)
You're forgiven - certainly calling out the lack of clarity was important!
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