On Thu, Feb 7, 2013 at 5:41 PM, Ross Paterson <r...@soi.city.ac.uk> wrote:
> On Thu, Feb 07, 2013 at 02:49:40PM -0800, Conal Elliott wrote: > > I make some use of arrow notation, though sadly I often have to avoid > > it because my (pseudo-)"arrows" don't have arr. I'd love to see a > > variant that has restricted expressiveness in exchange for arr-freeness. > > It's hard to imagine arrow notation without arr (or at least > contravariance in the first argument of the "arrow") because forming > expressions using the local environment is so central to it. That is, > I can't imagine what things you are trying to write in that situation. > What I have in mind is a small collection of methods including fst & snd (and similarly for sums) that could be defined via arr but could instead form the basis of translating restricted arrow notation for (pseudo-)arrows that don't support arr. I keep running into these pseudo-arrows in practical work. The reliance of arrow notation on arr means that I can't use arrow notation, and my code is terribly difficult to read. -- Conal
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