On Mon, 2008-12-08 at 09:58 -0800, Mark P. Jones wrote: > Don Stewart wrote: > > Which suggests that $ was already in the 1.0 report going to SIGPLAN. > > Perhaps Paul or Simon could shed light on it? Anyone have the 1.0 report > > lying around to check if it was in earlier? > > As far as Haskell is concerned, the first "report"-ed occurrence > of the $ operator was in the Haskell 1.2 report dated March 1992. > I don't see any mention of the $ operator in either the 1.0 or > the 1.1 reports (April 1990 and August 1991, respectively). > > The 1.0 report did define the following operator, which is a > variant of $: > > let :: a -> (a -> b) -> b > let x k = k x > > This was exported from the prelude, but its definition actually > appeared in the PreludeIO section of the report, hinting at the > main motivation for its introduction in support of continuation > based I/O. (Monadic I/O didn't officially arrive until the 1.3 > report in May 1996.)
Not officially, but `let' as above is in fact the unit of the Cont monad. And (>>>) from the PreludeIO section of the same report is the (>>=) for the Cont monad. So monadic I/O was there, it just seems that no-one noticed (or I haven't seen this explicitly pointed out)... jcc _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
