Syntax for output-only arrows?

John Meacham john at
Tue Jun 8 18:02:37 EDT 2004

On Tue, Jun 08, 2004 at 03:47:04AM +0300, Lauri Alanko wrote:
> 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.

ooh. I second this motion. if it is possible that is. 

John Meacham - ⑆⑆john⑈ 

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