> Brent Yorgey <byorgey <at> seas.upenn.edu> writes:
> >
> > data Oneple a = Oneple a -- (or newtype)
> > (Oneple $ CustId 47) -- too verbose
> >
>
> This is what the OneTuple package is for:
>
Thank you Brent, and Ivan made the same suggestion.
Apart from being more verbose (2 extra chars) than the approach I disliked
as being too verbose, does OneTuple have any merit?
> Dan Burton danburton.email at gmail.com
> Fri Aug 16 03:04:14 UTC 2013
claims that
> "T(CustId 47) is just one character off from what you actually want ..."
(Bare T is very likely to be used already.)
But not only do I want to construct Oneples, I also want to pattern match
and discriminate on their type in instances:
f (T(CustId x)) = ...
instance C (Oneple (CustId Int)) ...
I'm sensing there must be a need (since OneTuple is claimed to be a
solution for it).
Would double-parens be too wild an idea?:
... ((CustId 47)) `extend` (CustName "Fred", Gender Male)
f ((CustId x)) = ...
instance C ((CustId Int)) ...
We'd have to avoid the double parens as in:
((meth obj) (double x))
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