On 28 Jan 2010, at 03:09, Twan van Laarhoven wrote:
For example, in Map String Integer (sparse representation of
monomials) compute the minimum value of all associative pairs with
the same key (the gcd); if only one key is present, the absent
should be treated as having value 0. So
I need ideally some generalizations of unionWith and unionWithKey, for
efficiency matters (i.e. avoiding conversions and traversing the maps
more than once). I could use a modification of the code in Map.hs, but
then the problem is that the module Map interface does not export the
On Jan 27, 2010, at 5:53 AM, Hans Aberg wrote:
I need ideally some generalizations of unionWith and unionWithKey, for
efficiency matters (i.e. avoiding conversions and traversing the maps more
than once). I could use a modification of the code in Map.hs, but then the
problem is that the
On 27 Jan 2010, at 14:56, Jan-Willem Maessen wrote:
So here, one would want:
(a - c) - (b - c) - (a - b - c) - Map k a - Map k b - Map
k c
where the two first functions are applied when the first or second
key is missing.
Ah, the swiss army knife function on maps. This particular
On Jan 27, 2010, at 9:42 AM, Hans Aberg wrote:
On 27 Jan 2010, at 14:56, Jan-Willem Maessen wrote:
So here, one would want:
(a - c) - (b - c) - (a - b - c) - Map k a - Map k b - Map k c
where the two first functions are applied when the first or second key is
missing.
Ah, the swiss
On 27 Jan 2010, at 16:33, Jan-Willem Maessen wrote:
I'm not sure why you want to throw in functions between maps in the
two first arguments. Then there is no requirement that single keys
are preserved.
But it is a good idea to have a Maybe so that one can remove keys
on the fly.
A good
On Jan 27, 2010, at 10:54 AM, Hans Aberg wrote:
On 27 Jan 2010, at 16:33, Jan-Willem Maessen wrote:
I'm not sure why you want to throw in functions between maps in the two
first arguments. Then there is no requirement that single keys are
preserved.
But it is a good idea to have a
On 27 Jan 2010, at 21:29, Jan-Willem Maessen wrote:
I'm thinking about
(k - Maybe a - Maybe b - Maybe c) - Map k a - Map k b - Map k c
The first two Maybe's tell if the keys are present, the last if one
wants it in the resulting map.
That has the same behavior semantically, but it's no more
Hans Aberg wrote:
For example, in Map String Integer (sparse representation of monomials)
compute the minimum value of all associative pairs with the same key
(the gcd); if only one key is present, the absent should be treated as
having value 0. So
unionWith min xs ys
will not work, because
