Arrow notation vs RebindableSyntax

Ross Paterson R.Paterson at
Sat Mar 15 11:36:34 UTC 2014

On Thu, Mar 13, 2014 at 04:36:54PM -0500, Nicolas Frisby wrote:
> The 7.8-rc2 User Guide for rebindable syntax includes:
>     Arrow notation (see Section 7.16, "Arrow notation") uses whatever
>     arr, (>>>), first, app, (|||) and loop functions are in scope.
>     But unlike the other constructs, the types of these functions
>     must match the Prelude types very closely.  Details are in flux;
>     if you want to use this, ask!
> I want to use this: my types for the functions apparently do not match the
> Prelude types closely enough.
> Whom should I ask about this?

Daniel Winograd-Cort was looking at this, but I haven't heard anything
for a while.  My own view is that rebinding should be done at the control
operator level rather than the level of arrow combinators.  But what are
the types of your functions?

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