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the so called "purity" is achieved by using a higher kinded type and the cats IO monad. it's like adding "1+1" with a "mathematical-calculation-monoid-combine-f

the so called "purity" is achieved by using a higher kinded type and the cats IO monad. it's like adding "1+1" with a "mathematical-calculation-monoid-combine-factory-builder-singleton-locator-evaluator-pattern". I remember keeping it simple as an ultimate goal but maybe I am just too for this FP peeing contest? why is it such a frickin' deal to log a message somewhere?

the_af 5y ago
> why is it such a frickin' deal to log a message somewhere? Need I remind you of the Log4J debacle? It's definitely a big deal. Whether this is the right approach is another matter. PS: trust me, you don't need to read on category theory to use or understand monoids, which at the level they are used in Scala and Haskell code, they are trivial to understand.
doikor 5y ago
> I remember keeping it simple as an ultimate goal but maybe I am just too for this FP peeing contest? why is it such a frickin' deal to log a message somewhere? Don't know about others but for me it is about being able to easily verify that my logging is setup correctly. Once you write your logging to some monad (the library we use does not require it to be IO) testing it becomes trivial with a WriterT monad where it just write your logs into some list/buffer and check that what was logged in various cases was actually what you wanted. We do the same with tracing checking that spans are created as we wanted and the tags/logs on the spans are setup correctly.
- macpete42 5y ago
  Why would I verify logging which itself is a verification instrument? And, seriously, how hard is it to emit a diagnostic message so I need a test for that to get it right?
  - doikor 5y ago
    If you have some rare (rare as in it happens once every few months or something like that) error and you need logging about it. Also testing it ensures nobody by mistake removes that bit of logging by accident.
    - macpete42 5y ago
      code reviews would probably be a better fit to prevent that.
      - the_af 5y ago
        Code reviews are useful, but I've never seen them used as an argument against writing tests.
  - the_af 5y ago
    There are tests of tests, why wouldn't there exist techniques for the verification of logging?

the_af 5y ago

> why is it such a frickin' deal to log a message somewhere? Need I remind you of the Log4J debacle? It's definitely a big deal. Whether this is the right approach is another matter. PS: trust me, you don't need to read on category theory to use or understand monoids, which at the level they are used in Scala and Haskell code, they are trivial to understand.

doikor 5y ago

> I remember keeping it simple as an ultimate goal but maybe I am just too for this FP peeing contest? why is it such a frickin' deal to log a message somewhere? Don't know about others but for me it is about being able to easily verify that my logging is setup correctly. Once you write your logging to some monad (the library we use does not require it to be IO) testing it becomes trivial with a WriterT monad where it just write your logs into some list/buffer and check that what was logged in various cases was actually what you wanted. We do the same with tracing checking that spans are created as we wanted and the tags/logs on the spans are setup correctly.

macpete42 5y ago
Why would I verify logging which itself is a verification instrument? And, seriously, how hard is it to emit a diagnostic message so I need a test for that to get it right?
- doikor 5y ago
  If you have some rare (rare as in it happens once every few months or something like that) error and you need logging about it. Also testing it ensures nobody by mistake removes that bit of logging by accident.
  - macpete42 5y ago
    code reviews would probably be a better fit to prevent that.
    - the_af 5y ago
      Code reviews are useful, but I've never seen them used as an argument against writing tests.
- the_af 5y ago
  There are tests of tests, why wouldn't there exist techniques for the verification of logging?