[Haskell-cafe] Idiom Brackets for GHC (first full proposal)
roma at ro-che.info
Fri Feb 27 10:09:27 UTC 2015
On 27/02/15 09:58, Oliver Charles wrote:
> So you would argue that these should desugar to the same thing?
I guess I'm talking more generally here. On the one hand, I find this
practical and convenient. On the other hand, it (almost by design)
breaks our usual intuition of how the space works.
E.g. in most other cases id x is the same as x, but inside idiom
brackets they mean x and pure x, respectively.
I don't have a specific suggestion, just a concern.
> I'm on
> the fence - on the one hand its nice to be able to leave a few 'pure's
> out, but on the other those parenthesis have no syntactic meaning
> before, so it's questionable why they suddenly do inside idiom brackets.
> I can live with needing a few more 'pure's though.
> - Ollie
> On 26 Feb 2015 23:28, "Roman Cheplyaka" <roma at ro-che.info
> <mailto:roma at ro-che.info>> wrote:
> I'm starting to like this. Except the weird difference between spaces on
> different levels that you point out, i.e.
> [| const True False |]
> [| (const True) False |]
> On 26/02/15 23:04, Oliver Charles wrote:
> > Hi all,
> > A few days ago I made a post here to gauge interest in adding idiom
> > brackets to GHC. Response was a bit more mixed than I was hoping,
> but no
> > one seemed to drastically against the idea, so I've moved forward
> with a
> > more detailed proposal.
> > You can find the full proposal here:
> > https://ocharles.org.uk/IdiomBrackets.html
> > A particular difference in my proposal from existing solutions comes
> > from my desire to lift almost *all* expressions - with the original
> > syntax - into idiom brackets. This means normal function
> application and
> > tuples, but also case expressions, let bindings, record construction,
> > record update, infix notation, and so on.
> > At first I was skeptical about this, but I am finding uses for
> this more
> > and more. I really like how it lets me use the interesting data (that
> > is, whatever is "under" the applicative functor) where it's most
> > relevant - rather than having to build a function and thread that
> > back through. Examples of this can be seen in my proposal.
> > To prove its use, I've been working with this Template Haskell
> > expression:
> > https://ocharles.org.uk/IdiomExp.hs
> > It *almost* does exactly what I want, the only problem is I can't get
> > Template Haskell to give me a difference between
> > $(i [| const True False |])
> > and
> > $(i [| (const True) False |])
> > which I was planning to be significant.
> > The proposal has mostly grown into my own personal notebook, so I'm
> > happy to clarify anything that is vague/contradictory/confusing.
> > Look forward to hearing your thoughts!
> > -- Ollie
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