Re: Extending the do-notation

7 Jan 2001

      Sebastien Carlier wrote:
...
Sometimes I need to write code which looks like this:
...
do x <- m1
      let y = unzip x
      ... -- never using x anymore
I thinks the following extension to do-notation would be useful:
...
pat <- exp1 # exp2 ; exp3
would be rewritten as
   exp2 >>= ((\pat -> exp3) . exp1)
so that the above example could be rewritten more compactly:
...
do y <- unzip # m1
This can be done in Haskell without any changes to the
'do' notation at all:  just define

|	f # m = m >>= (return . f)

and add an appropriate fixity declaration for '#'.

--Joe English

  jenglish@flightlab.com