In ML you can get a similar terseness to that of Haskell, but with support for imperative programming. If we allow the increment function to be predefined (as the Arc example does):

 let inc a b = a := !a +/ b; !a

then foo becomes:

 let foo n = inc (ref n)

or, with the help of the composition operator:

 let (<<) f g x = f (g x)

 let foo = inc << ref