and they all have easy, one-line, correct examples of how to do it, within the first 20 seconds of reading.
(This is not to criticise -- sometimes one misses the forest for the trees -- as a professional Haskell consultant who runs trainings I am genuinely interested into what problems people face and why.)
What method did you try to figure it out?
If I google "haskell debug print pure function", the first three results I get are:
* https://hackage.haskell.org/package/base-4.12.0.0/docs/Debug...
* https://stackoverflow.com/questions/13265783/trace-output-in...
* https://en.wikibooks.org/wiki/Haskell/Debugging
and they all have easy, one-line, correct examples of how to do it, within the first 20 seconds of reading.
(This is not to criticise -- sometimes one misses the forest for the trees -- as a professional Haskell consultant who runs trainings I am genuinely interested into what problems people face and why.)