DData in hierarchical libraries

Christian Maeder maeder at tzi.de
Fri Feb 20 15:49:23 EST 2004

JP Bernardy wrote:

>   >map (append q1) listOfQueues
>   means that q1 is "prepended" to each queue.
> * Rename subset & friends.
>   Similarly, they have an implicit infix meaning.
>   >filter (subset s1) listOfSets
>   actually keeps sets that are supersets of s1.
>   Is there an agreed-upon (operator) name for this?

The problem with operator names is that they look ugly when qualified 

Surely partial application "(subset s)" is different from a section 
"(`subset` s)" but is something that a Haskeller must learn anyway!

Guess which argument "r" is in the instance "Functor ((->) r)". (This 
took me an age.)

> * Make maps look more like collections of couples.

It's seems Haskell tradition to curry as much as possible (though this 
makes arguments and results non-symmetric, as in "quotRem" and "divMod")

> * rename (<>) to (++)

Ok, but see above. Both a symbolic and a letter name are fine (like 
difference and \\).

> * Make some types instances of Ord and Functor.


Furthermore: "MultiSet" should be named "Bag", Daans remark "that 
equality on elements should be defined as a structural equality instead 
of an equivalence relation." already applies to Set and Map! (Or may 
equal set look different when printed out?)

Just my single cent,

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