implement streaming helpers to for/map/grep/reduce all lines in a file

[wchristian]

This is a first sketch to suss out things we want or do not want.

@ingydotnet , @frioux , @shadowcat-mst : Please comment and bikeshed.

[frioux]

I like and agree with what @ingydotnet said about just naming them for/map/grep/reduce, instead of including lines, so that they could have alternate meanings when used with, for instance, a directory object.

[wchristian]

Alright, that makes sense.

I renamed them and updated the code to be able to handle streaming arbitrary items off various io object types.

What are the streaming methods for the other object types?

[wchristian]

I just noticed we already have one related thing:

my @odd = io->curdir->filter(sub {$_->size % 2})->All_Files;

[shlomif]

hi! It seems that documentation ought to be added.

[wchristian]

Hey @shlomif, as the previous comments indicate, this is just an RFC prototype, and i was hoping to get more input from @ingydotnet , @frioux , @shadowcat-mst and any other interested parties before fleshing it out, but it kind of fell by the wayside.

If you'd read through the proposed code and opine on whether it makes sense as it is, and maybe look at the other questions raised, i'd be happy to move forward with it. (Though at this point i would need to refamiliarize myself as well.)