Re: Re: [Haskell-cafe] A type class puzzle

Rearranging... Nicolas Frisby wrote:

On 10/31/06, Greg Buchholz wrote:

...

...That first article is the strangest. I couldn't reconcile the fact that if our type signature specifies two arguments, we can pattern match on three arguments in the function definition. Compare the number of arguments in the first and second instances...

See Connor McBride's "Faking It: Simulating Dependent Types in Haskell" http://citeseer.ist.psu.edu/mcbride01faking.html

It might help; your example makes me think of the "nthFirst" function. If it's different, I'md wager the polyvariadic stuff and nthFirst can be reconciled on some level.

Does that explain how, why, or when you can use more arguments than you are allowed to use? Or is it just another example of "using more arguments than you are allowed to use"? Is this a Haskell 98 thing, or is it related to MPTCs, or fun deps, or something else? Greg Buchholz