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