In my opinion, when you are rebinding a variable with the same name, there is usually another way to structure your code which eliminates the variable.
If you would like to write: let x = foo input in let x = bar x in let x = baz x in instead, write baz . bar . foo $ input If you would like to write let (x,s) = foo 1  in let (y,s) = bar x s in let (z,s) = baz x y s in instead, use a state monad. Clearly this will not work in all cases, but it goes pretty far, in my experience. Edward Excerpts from Andreas Abel's message of Wed Jul 10 00:47:48 -0700 2013: > Hi Oleg, > > just now I wrote a message to haskell-pr...@haskell.org to propose a > non-recursive let. Unfortunately, the default let is recursive, so we > only have names like let' for it. I also mentioned the ugly workaround > (<- return $) that I was shocked to see the first time, but use myself > sometimes now. > > Cheers, > Andreas > > On 10.07.2013 09:34, o...@okmij.org wrote: > > Andreas wrote: > >> The greater evil is that Haskell does not have a non-recursive let. > >> This is source of many non-termination bugs, including this one here. > >> let should be non-recursive by default, and for recursion we could have > >> the good old "let rec". > > > > Hear, hear! In OCaml, I can (and often do) write > > > > let (x,s) = foo 1  in > > let (y,s) = bar x s in > > let (z,s) = baz x y s in ... > > > > In Haskell I'll have to uniquely number the s's: > > > > let (x,s1) = foo 1  in > > let (y,s2) = bar x s1 in > > let (z,s3) = baz x y s2 in ... > > > > and re-number them if I insert a new statement. BASIC comes to mind. I > > tried to lobby Simon Peyton-Jones for the non-recursive let a couple > > of years ago. He said, write a proposal. It's still being > > written... Perhaps you might want to write it now. > > > > In the meanwhile, there is a very ugly workaround: > > > > test = runIdentity $ do > > (x,s) <- return $ foo 1  > > (y,s) <- return $ bar x s > > (z,s) <- return $ baz x y s > > return (z,s) > > > > After all, bind is non-recursive let. > > > > > > > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe