Avoiding construction of dead dictionaries

Claude Heiland-Allen claude at mathr.co.uk
Mon Aug 9 16:00:28 UTC 2021

Hi all,

On 09/08/2021 16:31, Brandon Allbery wrote:
> We haven't figured out what they did, but the other day we had someone 
> in #haskell with an infinite loop evaluating a dictionary. So 
> apparently it is possible for a dictionary to be bottom somehow.

I managed to do something like this once: I was using type level natural 
numbers to parameterize my type, and through carelessness my dictionary 
for `T n` depended on the dictionary for `T (Succ n)`.  My heap profile 
was a triangular wedge with space taken up by dictionaries growing 
linearly without bound.




More information about the Glasgow-haskell-users mailing list