Context for typed holes

Christopher Allen cma at
Fri Oct 23 05:35:30 UTC 2015

It's not just you. That's why I didn't mention holes in the book as people
suggested. It's not just confusing for new people - it drives me nuts every
time I use a hole in non-trivial code at work.

On Thu, Oct 8, 2015 at 6:25 PM, David Feuer <david.feuer at> wrote:

> Unless something has changed really recently that I've missed, the typed
> holes messages are missing some really important information: instance
> information for types in scope. When I am trying to fill in a hole, I look
> to the "relevant bindings" to show me what pieces I have available to use.
> Those pieces don't include contexts! Is there something fundamentally hard
> about adding this information? I'd only want instance information for type
> variables--providing it for concrete types would make too much noise. I'd
> also want information on equality constraints, of course.
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Chris Allen
Currently working on
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