[Haskell-cafe] Picking an architecture for a Haskell web app

[Neil Mitchell]

Hi Andrew,

> > Also remember that evaluating an expression in Haskell is _really_
> > hard!
>
> Really? Looks pretty damn simple to me...

In that case I throw down the challenge of writing an interpetter that
takes a Haskell syntax tree and evaluates it :)

What is the value of show [] ? Remember that show ([] :: String) /=
show ([] :: [Bool), so I can't see how you can drop the types and keep
the semantics. I would love to write a Haskell interpretter which
didn't deal with types (crashing at runtime for ill-typed is fine) -
unfortunately I couldn't make it work because of this. If you figured
it out, please share!

> Oh, yeah, well, definitely the hardest part is *parsing* Haskell. In
> particular, the fact that layout exists makes this problem essentually
> unsolvable.

I'd say the type checking was much harder. The problem of desugaring
is broad, but in most cases isn't that complex.

Thanks

Neil