[Haskell-cafe] A very nontrivial parser

Andrew Coppin andrewcoppin at btinternet.com
Sun Jul 8 08:31:32 EDT 2007

Brandon S. Allbery KF8NH wrote:
> On Jul 8, 2007, at 8:12 , Andrew Coppin wrote:
>> Aye, you drive a car without knowing how it works - but it was put 
>> together by some people who *do* know these things. Would you drive a 
>> car you built yourself? ;-)
> No :) --- but depending on what you're doing, you can use rank-2 types 
> without knowing what's under the hood.  In fact, I'd say the fact that 
> you're using them is evidence of that.
> (Aside --- looking at your problem description, I wonder if GADTs 
> would be a better fit.)

Oh, I don't mind not knowing how rank-2 types are *implemented*. ;-) But 
it would be nice to know what they *are*... :-S

(Thus far, they just seem to be some incomprehensible syntax that makes 
the compiler stop complaining. In particular, I have no idea what the 
difference between rank-2, rank-N and existentially quantified is...)

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