[Ur] TechEmpower Benchmarks

[escalier at riseup.net]

> As I understand the Ur/Web benchmark code, it will automatically  
> pick up this change as part of its deployment procedure.

Yes, it should.

> Do you know what value the 'max_threads' parameter is being  
> instantiated with in practice?

Based on the logs, it looks like 8. But I would imagine it will vary  
from platform to platform in the actual benchmark.

> List.mapM -> List.app

Thanks. I've made the change locally, but I think I'll wait to push it  
till next round. (I briefly looked for such a function when initially  
writing the code. Just for your information, in Haskell, `app` is  
known as `mapM_` following a convention that a trailing underscore  
discards the result of a monadic action.)