Simon Peyton-Jones wrote:
| <cite> | The let-binding can be recursive. However, it is much more common for | the let-binding to be non-recursive, in which case the following law | holds: (let !p = rhs in body) is equivalent to (case rhs of !p -> body) | </cite> | | Shouldn't the bang be removed in the final case pattern?
No. If p was a simple variable, then case rhs of x -> body is non-strict in Haskell, but should be strict here.
Thanks for pointing this out. But the case with a simple variable (and no distinction) is special anyway (sort of a monomorphic let binding).
| P.S. It should be mentioned that ~ and ! only make sense for single | variant data types (like tuples)
That isn't true. Both are useful for multi-variant types
Right, a non-empty list should behave like a pair as long as I don't want to know the variant beforehand and thereby forcing evaluation anyway. Cheers Christian