Add mkString to HList and tuples

[stacycurl]

No description provided.

[milessabin]

This doesn't look quite right ... why is there ToList-related stuff in this PR?

[milessabin]

Aside from the stray ToList stuff that's got itself into the mix this looks fine ... I'll merge when you've sorted that out. Thanks :-)

[stacycurl]

The ToList for tuples had an unconstrained output type, unlike that for hlists which states that the result is a List[Lub]. The implementation relies on converting to a List before calling mkString on it, I can't call mkString on an arbitrary type.

Of course I could add a MkString type class for tuples but I figured that the return type for ToList should be List[Lub].

[milessabin]

OK, gotcha ... I'm going to hold off on this until #119 is merged.

[milessabin]

Could you rebase this now that #119 has been merged?

[milessabin]

Whoops ... it was #114 I merged, not #119 ... still pending.

[milessabin]

I think that #119 should subsume your ToList change.

As an aside, I would prefer that type class signature to have been written as,

trait ToList[T, Lub] extends DepFn1[T] { type Out = List[Lub] }

[milessabin]

Could you update this now that #119 has been merged? :-)

[stacycurl]

Updated

[milessabin]

Cool ... I'm not persuaded by the defaulted variants though. I think .mkString() should equal .toString (which makes it fairly useless) and that if you want to specify any of the prefix, separator and suffix you'll want to specify them all (especially given the choice of "⸨" and "⸩" as the default prefix and suffix ;-)

[stacycurl]

Grr, updated. It's a simpler commit now but I still think ⸨⸩ are brilliant delimiters for a hlist, like a tuple but more so !

I had the 3 variants to mimic those on Traversable.

[milessabin]

Less is more ;-)

Merging now ... many thanks ... much appreciated :-)

[kevinwright]

Don't worry stacy... I once tried to use «» for the interpolation in boilerplate, and was told it was "too cute". You're not the only person to experience unicodophobia here :)

[milessabin]

:D