fa-ml at ariis.it
Tue Dec 13 15:23:29 UTC 2016
On Tue, Dec 13, 2016 at 02:36:39PM +0000, mike h wrote:
> I’m trying to sort a list of tuples. A char and a count of that char (Char , Int)
> [ ('r',2), ('c',2),('a', 2), ('b',3), ('f',2)]
> e.g. ‘r’ occurs twice etc.
> The order should be based on the count first and then ties broken by the
> natural ordering of char.
You should provide sortBy with an appropriate compare function, e.g.
comp (a,b) (c,d) | a > c = GT
| -- etc etc.
or go with the manky but working hack:
λ> :m Data.List
λ> sortOn (\(a, b) -> b*(-100) + fromEnum a) [('r',2), ('c',2),('a', 2), ('b',3), ('f',2)]
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