[Haskell-cafe] [Alternative] summary of my understanding so far

[Matthew Farkas-Dyck]

On 16/12/2011, Gregory Crosswhite <gcrosswhite at gmail.com> wrote:
>
> On Dec 17, 2011, at 12:35 PM, Matthew Farkas-Dyck wrote:
>
>> (1) If we do (4), then the documentation ought to be adequate as-is.
>
> I see your point that if we do (4) then some and many are no longer
> problematic for Maybe and [], and thus we don't need warnings for those
> types.  However, nonetheless we will *still* need *big warnings* *for the
> sake of others who write Alternative instances* for new types to make sure
> that these instances do not fall into the same trap as Maybe and [].  That
> is, we want to let future authors of instances know about the conditions
> under which they will need to write their own versions of some and maybe in
> order to make sure that these methods have sensible behavior.

> Finally, if we adopt (4) then we will need to change the documentation to
> remove "least" from "least solutions of the equations" since the phrase will
> no longer be correct.  Better still, we could replace the phrase entirely
> with something like "least *converging* solutions of the equations". (*)

Ah, true. Sorry.

> In addition to this, we also really need some additional documentation
> explaining what the point of some and many are, since few people have any
> clue about them.  :-)

Myself, I think it's quite clear by the axioms given, but I certainly
shan't grouch about more/better documentation.

> Cheers,
> Greg
>
> (*) P.S:
>
> Dear people who are better at this kind of technical language than I:
>
> I am fully aware of the fact that the phrase "least converging solutions of
> the equations [...]" is sloppy wording at best and absolutely wrong at
> worst, but hopefully you should at least understand what I am *trying* to
> get at.  Thus, I would welcome either your feedback on what it is that I am
> supposed to be thinking and saying, or an explanation about why the idea I
> am trying to conceive and convey is so intrinsically poorly formed that I am
> best off just giving up on it.  ;-)

Actually, now that I think of it, they are not, in general, the least
converging solutions -- in the case of a parser, for example, (some
(pure x)) would nevertheless diverge (I think).
Perhaps "least sane solutions" (^_^)

Cheers,
Matthew Farkas-Dyck