When I use arrows, I find that many of my primitives are of type (a () b) (for some arrow type a): they produce a value but don't take any input. E.g. deterministic parsers are like this. The syntactic sugar for arrows is lovely, but I find it a bit tedious writing "foo -< ()" all the time. The syntax allows the output of arrows to be ignored, why not input too? Would it cause unreasonable parsing problems simply to allow a simple expression of an arrow type to be a legal command inside a proc expression, with an implicit -< () input? Or are there other reasons against it? I for one find it extremely convenient that I can write "purely imperative" code with a simple syntax like do { foo; bar; baz }. I'd like similar simplicity when dealing with arrows, too. Lauri Alanko la@iki.fi