[Haskell-cafe] Diving into the records swamp (possible GSoC project)
anthony_clayden at clear.net.nz
Sat Apr 27 12:41:18 CEST 2013
> Johan Tibell <johan.tibell <at> gmail.com> writes:
> The discussions about an overhauled record system also involve lots of
talk about record sub-typing, extensible records, and other more advanced
features. I'd like to point out that there doesn't seem to be a great
demand for these features. ...
Sorry, Johan, I really have to disagree with that.
There's lot's of Haskell to SQL interfaces that build on HList and its
extensible record ideas (HDBC for example).
But the usability is not good (as Petr points out, and as Oleg/Ralf
admitted back in the paper). The type error messages are long and obscure.
> ... They might be nice-to-haves or might fall out naturally from a
solution to the namespacing problem above, but they are in fact not needed
to solve the common problem people have with the Haskell record system.
"the common problem people have" is that the record system is unusable
[IMO] so doesn't get 'stretched' to see what other difficulties it has.
There are all sorts of alternative systems (including Lenses) built with
Template Haskell (and chewing gum and gaffer tape: that's how desperately
bad is the current situation ;-).
I'm saying that many people find the Haskell record system 'as is' so
dysfunctional that they give up on it! I feel strongly that as soon as we
get past the name collissions, there'll be other blockages to using it.
I'd be interested to hear if there are any who can remember the Trex
system, and how (un)usable it was?
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