[Haskell] Re: RFC: DData in hierarchical libraries

Daan Leijen daanleijen at xs4all.nl
Fri Mar 12 15:28:32 EST 2004

Simon Marlow wrote:
> Just as a matter of personal preference, I find a right bias 
> to be more intuitive.  Also, if the map argument comes first 
> in 'insert map key x', then partial application is more 
> likely to be useful (you're more likely to be inserting 
> several things in the same map, rather than the same thing in 
> several maps).

This makes a lot of sense!, even when it is inconsistent with
"List.elem" (we could argue that List.elem is just wrong :-)

So we can do supposedly common things like:
  any (member s) xs
  map (lookup m) ks
(But I think I can also come up with partial applications where
the current design is nicer so I don't think we should get into
long discussions about which partial application occurs more often
unless we can back it up with data :-)

Personally, at the moment, I like "right-bias with structure arguments
coming first"
more -- so if many others like it better too, I might be persuaded to
the implementation. However, this requires quite a bit of work, so I
would like
to leave this issue open for discussion for a while.

All the best,

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