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
On Tue, Oct 18, 2005 at 05:51:13PM +0100, Conor McBride wrote:
| Neither Oleg nor Bruno translated my code; they threw away my
| structurally recursive on-the-fly automaton and wrote combinator parsers
| instead. That's why there's no existential, etc. The suggestion that
| removing the GADT
[EMAIL PROTECTED] wrote:
I suspect that once you start producing values with the
relevant properties (as I do) rather than just consuming them (as Oleg
and Bruno do), the GADT method might work out a little neater.
Actually, the code is pretty much your original code, with downcased
On Wed, Oct 19, 2005 at 03:17:41PM +0100, Conor McBride wrote:
I was just about to send, when up popped Ross's program, which does give
me a datatype, including just enough extra stuff to support functoriality.
data RegExp tok a
= Zero
| One a
| Check (tok - a) (tok - Bool)
On Wed, Oct 19, 2005 at 03:17:41PM +0100, Conor McBride wrote:
It's nice that the syntax of regular expressions survives, but it
has been somewhat spun in favour of the functionality required in
the example.
I'm not sure about that either -- the existential coding supports
elimination too, if
Hello,
You can also write this code in Haskell 98. Jeremy Gibbons and I have
recently written a paper entitled TypeCase: A design pattern for
type-indexed functions where we explore the use of some techniques from
lightweight approaches to generic programming (Ralf Hinze and James
Cheney's work)
Hi folks
There is nothing ingenious with this solution --- I basically translated
Oleg's and Conor's code.
Neither Oleg nor Bruno translated my code; they threw away my
structurally recursive on-the-fly automaton and wrote combinator parsers
instead. That's why there's no existential, etc.
Conor McBride wrote:
Neither Oleg nor Bruno translated my code; they threw away my
structurally recursive on-the-fly automaton and wrote combinator parsers
instead. That's why there's no existential, etc. The suggestion that
removing the GADT simplifies the code would be better substantiated
Conor McBride wrote:
Neither Oleg nor Bruno translated my code; they threw away my
structurally recursive on-the-fly automaton and wrote combinator parsers
instead. That's why there's no existential, etc. The suggestion that
removing the GADT simplifies the code would be better substantiated
The code seems a bit simpler, too.
Do you really think so? To me replacing a GADT by class and
instance declarations seems the wrong way round. We should
not forget that the DT in GADT stands for `data type'. One
could certainly argue that the gist of functional programming
is to define a
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