[Haskell-cafe] Indentation woes

[anon]

Greetings,
I wish to be able to indent my code like so:
> longFunctionName various and sundry arguments
> | guard1 = body1
> | guard2 = body2
> | ...
> where declarations
That is, with guards and where clauses indented to the same level as
the function name.

This seems like a perfectly reasonable indentation style to me. It
also happens to be the preferred style in Clean, another
layout-sensitive functional language. I believe it is not uncommon in
ML dialects as well. So why is it that I'm not allowed to use it in
Haskell?