std.algorithm's remove

[maarten van damme]

But remove doesn't truly remove from the source range because the length of
the source range stays the same. It's return value is a modified copy of
the source range.

Filter doesn't really work right away because that would also remove
duplicate elements while I only want to remove at a given index. It also
makes for clunkier looking code and is counterintinuitive to come up with
(I want to remove an element therefore I have to filter every element that
isn't equal to that element from the source range...)
And while I haven't worked in c++, even that appears to have remove_copy
which is really what I want.

I could use temporary variables and blow that neat line up in 3 lines
which, while still readable, look redundant.

I'm happy the d result is 3 times shorter then their haskell solution but
not that the time spent was 5 minutes working and the rest of the time
debugging. This as opposed to using racket where the time spent is 15
minutes but after that everything works great (while my racket experience
is limited to playing around with it for 2 weeks now and then).


2013/8/25 Brad Anderson <eco at gnuk.net>

> On Sunday, 25 August 2013 at 02:24:30 UTC, maarten van damme wrote:
>
>> hello,
>>
>> I'm a hobyist-programmer and around where I live there's a group of
>> haskell
>> fanatics. They posted solutions to a recent programming challenge which I
>> find to be a bit ugly. For fun I wanted to implement it in d and a rough
>> version (not correct yet, this was written/hacked in 5 minutes after
>> reading the exercise)
>>
>> My rough version is posted here : http://dpaste.dzfl.pl/4b5a6578
>>
>> if you look at the output, you'll see this particular line :
>> "omkom -> komkom because of : kom momkom momkom -> momkomm"
>>
>> This is because of what remove from std.algorithm does. It not only
>> returns
>> a range with that element removed (as the name implies), it also modifies
>> the original range.
>> I assume this decision was made for efficiency purposes but that is one of
>> the most ugliest things I have ever come across. At least c# forces the
>> 'ref' in it's parameters so you know something's up. Is there any way I
>> could've known this? (apart from reading the documentation on every single
>> trivial function in the std library?)
>>
>
> It was done that way intentionally because the purpose of remove is to
> remove from the source range.  If you don't want to affect the source range
> use filter.
>
> I suspect you could trace remove's lineage back to C++ STL's remove which
> works similarly (but is significantly clunkier and harder to use).
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puremagic.com/pipermail/digitalmars-d-learn/attachments/20130825/7be55c51/attachment.html>