Warn when productivity is low

[andreiburdusa]

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Fixes #1988

Reviewer checklist

• Test coverage: stack test --coverage
• Public API documentation: stack haddock

[ana-pantilie]

Is it possible to use the logger to issue a warning for this?

[andreiburdusa]

Is it possible to use the logger to issue a warning for this?

That would require IO to be an instance of MonadLog and by looking at the class definition I think it was intended to instantiate only transformers 🤔, but I don't know.
Also, I thought the logger is for user-relevant information

[ana-pantilie]

LoggerT is MonadIO so you could get the stats and log them inside the logger, but it might be that you would want to access this information only at the very end of execution. Would that be the case here?

[andreiburdusa]

LoggerT is MonadIO so you could get the stats and log them inside the logger, but it might be that you would want to access this information only at the very end of execution. Would that be the case here?

Oh, I thought by "logger" you mean the entire logging mechanism.

@ttuegel Can the warning be moved as Ana suggested?

[ana-pantilie]

Is there any reason we don't want to add a separate entry type, WarnIfLowProductivity, instead of logging this as a LogMessage?

[andreiburdusa]

parsimony :))
I'll add a new entry type 👍

[ana-pantilie]

Approved and added a refactoring commit, please take a look when you have time.