[touisteur]

On the other end I'm endlessly tired of 'too simple' foreach/map iterators. They're OK until you want to do something like different execution on first and/or last element... Give me a way to implement a 'join' pattern over the foreach iterators, or less terse iterators (with 'some' positional information). I think I'm just ranting about the for-of iterator in Ada...

[Jtsummers]

Ada provides a kind of iterator called a Cursor which could be used to build up a package of functions similar to the various C++ standard library algorithms. I believe this has actually already been done. Cursors can also be converted back to positional information if it makes sense (like with a Vector).

[touisteur]

I like the cursor, because it abstracts indexes. Problem is, if I want the element, I still have to go fetch it (calling Element on the Cursor) and then I have to save it in a local variable and then I need to add a declare block for the constant standing for the result of Element and then the thing makes 5 lines instead of two and is not much more readable. Maybe I can just use Element() (especially since AdaCore seems to want to generalize dotted notation) repeatedly and have it inlined, but my past experience says 'expensive'...

And sadly Cursors haven't been generalized to all associative iterable structures in Ada (arrays for example).

[DougBTX]

I quite like the “enumerate” pattern. When indexes matter, instead of `for x in v` you would write, `for (i, x) in enumerate(v)`, then the language only needs one type of for loop as both cases use the same enumerator interface.

[touisteur]

Yes I was thinking of something like that. Only I wish I could also know whether I is first and/or last without calling into the iterated structure. I know this looks like corner case syntactic sugar but it comes up a lot, e.g. when serializing to JSON. I guess I should write my own iterators but I want them everywhere...