[tel]

Every monad is also an applicative and liftA2 does/is the same thing as liftM2. The only reason they both exist was due to Monad being popularized in Haskell earlier than Applicative and thus not having it as a superclass until the Functor-Applicative-Monad Proposal in Haskell 2014. It was obviously correct, but a major breaking change that also got pork barreled a bit and so took a while to land.

[solomonb]

Yes you're absolutely right. I had a bit of a brain fart moment here. If they were Applicative operations then you would not be able to use `liftM2`, not the other way around.

[mnsc]

This is my fear when I think about doing actual in a team using a functional language. That there's an imbalance in understanding between participants in a team making all discussions about problem x into the pattern matchning problem y. Like "is this liftM2 or liftA2?"

I've only had a couple of months of experience working with scala before the team switched to Java. The reasons were many but one of them was that the external consultant that was most knowledgeable in "thinking with functions" was kind of a dick. Making onboarding into a horror show of "go look up yt video x before I can talk about this functionality" with a condescending tone. So within a month he was let go and then no one in the remaining team really had the courage to keep debe it further. Some thought that they maybe could maintain the current functionality but the solution was only like half complete. (in the consultant mind it was complete because it was so generic you only needed to add a couple of lines in the right place to implement each coming feature)

That said, I would love to work in a hardcore Haskell project with a real team, one with a couple of other "regular" coders that just help each other out when solving the actual problems at hand.

[solomonb]

Well, I can't speak to your experience but in the case of liftM2 vs liftA2 I have never even seen liftM2 get used. Its more of a historical oddity that it is available.