std.algorithm missing for_each?

[Jens Mueller]

Jakob Ovrum wrote:
> On Wednesday, 5 February 2014 at 10:03:52 UTC, Jens Mueller wrote:
> >Dear lovely D community,
> >
> >recently I refactored some code into component style (see
> >Component
> >Programming in D by Walter
> >http://www.drdobbs.com/architecture-and-design/component-programming-in-d/240008321)
> >
> >It looks about like this
> >
> >someInputRange
> >.filter!()
> >.map!()
> >
> >Next I want to discard all elements but perform some last
> >operation on
> >each element. The problem is that map forces me to pass a function
> >that
> >returns. Of course I could return a fake value. But that doesn't
> >look
> >proper. Another option is to iterate using the foreach loop. Does
> >not
> >look better either, does it?
> >
> >This makes me believe that std.algorithm misses an algorithm. The
> >for_each algorithm (see for_each in STL
> >http://www.cplusplus.com/reference/algorithm/for_each/).
> >
> >To rephrase the problem more general (because maybe I'm just not
> >seeing
> >how to fit the pieces together): How do you perform some arbitrary
> >operation on the elements of a range?
> >
> >myRange
> >.each!((e)
> >{
> >	e.someOperation();
> >});
> >
> >Jens
> 
> Consuming an input range in the functional style should be done by
> std.algorithm.copy (passing an output range) or by simply passing
> the input range to the consumer algorithm.
> 
> Sometimes this isn't possible, which means reverting to foreach,
> i.e. a mix of functional and imperative style. This is the
> equivalent of STL's `for_each`.
> 
> I think adding an `each` function to Phobos is problematic. It is
> syntax sugar for foreach, but with the downside of obfuscating what
> is essentially imperative code. IMO, imperative code should look
> like imperative code, which with foreach is by no means ugly.

Rephrasing your words to get a clear image for myself: You argue that

foreach (e; someInputRange
            .filter!()
            .map!())
	e.someOperation();

is not ugly and the way to go.

And

someInputRange
.filter!()
.map!()
.each!();

is bad because it mixes two styles.

Jens