[Haskell-cafe] Regular Expressions without GADTs

Bruno Oliveira Bruno.Oliveira at comlab.ox.ac.uk
Wed Oct 19 04:57:03 EDT 2005

Hello Conor,

I personally think GADTs are a great idea, don't get me wrong. I am not arguing
that we should all start programming using on a Church encoding. Neither I
am arguing that this encoding can replace GADTs in all cases.

Nevertheless, I believe that knowing about this encoding, in the first
place, can be extremely valuable for programmers. Let's not forget that neither
GADTs or multiple parameter type classes are Haskell 98! In fact, as far as
I understood from the Haskell Workshop, we are a long way from those extensions
becoming standard. My point is that if you are developing software,
then you want to use something standard (this is, running on Hugs, Nhc,
Ghc, Ehc, ...).
This encoding tries to avoid extensions (not saying that it does for all

In the end, that is what most design patterns are: workarounds on missing
language features. In this case missing features of Haskell 98 (but not
GHC Haskell).

Best Regards,

Bruno Oliveira

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