On Fri, 2007-11-02 at 11:56 -0400, Brandon S. Allbery KF8NH wrote:
On Nov 2, 2007, at 11:51 , Jonathan Cast wrote:
I will grant that hiding *World / RealWorld# inside IO is cleaner from a practical standpoint, though. Just not from a semantic one.
On the contrary. GHC's IO newtype isn't an implementation of IO in Haskell at all. It's an implementation in a language that has a Haskell-compatible subset, but that also has semantically bad constructs
Differing viewpoints, I guess; from my angle, Clean's "uniqueness constraint" looks like a hack hidden in the compiler.
Yeah. After all, the "uniqueness constraint" has a theory with an excellent pedigree (IIUC linear logic, whose proof theory Clean uses here, goes back at least to the 60s, and Wadler proposed linear types for IO before anybody had heard of monads). It's not some random hack somebody happened to notice would work, any more than existential types are. jcc