And it's not just the statement. It seems to me (from my outside perspective) that category theory is often used in a gatekeeping way.
In contrast, take SQL. How much of the mathematical theory of relations do you need to know to be able to write SQL queries? Yes, it might help, but the SQL gurus don't try to drag you into it every time you get close to a database.
The original attribution of this line about monads comes from the (intentionally) comedic article "A Brief, Incomplete, and Mostly Wrong History of Programming Languages", published by James Iry in 2009: http://james-iry.blogspot.com/2009/05/brief-incomplete-and-m...
It is not a stance I have ever seen taken up in a serious manner by anybody in the FP community, and I work in PL academia (the region of the community from which I would expect to see the most snobbery). Please stop misrepresenting people based on a misunderstood joke.
There are people in the FP community who gatekeep and take on a snobbish tone — with that I do not disagree. However, their prevalence is generally overstated; it's a vocal minority situation. Most people I know or have talked to are very welcoming.
The actual quote that monads are monoids in the category of endofunctors comes from MacLane, and is intended for mathematicians.
Although the abstract phrasing can be traced to him, the particular use of "just" in the parent comment's quote tells me they're specifically thinking of the (deliberately condescending) version from the Iry post, especially since that's the version that gets memed throughout the FP community. After all, that particular phrasing is meant to convey a sense of "this is obvious and you are stupid if you don't understand it immediately", which is a far cry from the MacLane version (since that one is, as you said, intended for mathematicians).
But I probably ought to have included the full provenance regardless; thank you for bringing it up!
The saying "a monad is just a monoid..." is a cliché and an in-joke, not gatekeeping. It's the community having a laugh at itself.
The years have proven that ease of programming and the burden of knowledge are the two most important elements of a programming language. FP zealots simply won't accept that their chosen paradigm is opaque to most for benefits that can't seem to be written out in human language.
On this website you will hear anyone say the wildest assertions. There's the whole human range of expression here. But what makes you think actual FP practitioners (and Haskelers) really believe this?
The proof wouldn't be what some random person here on HN tells you. The proof would be you getting involved in an actual FP community trying to write an actual FP project and being told that you just cannot do this unless you understand category theory. Which, as I said, is not something that happens... at least not in my (limited) experience.
Never confuse what people tell you here on HN, random forums or even throwaway StackOverflow comments with what actually happens in the actual communities when trying to achieve real goals and not just chat about stuff.
> Nobody claims you have to understand category theory to write Haskell.
I've seem the claim that you can't really use Haskell without it, here on HN, more than once. (Or at least something that I interpreted as being that claim...)
Gatekeeping would be if the community said this with a straight face and everyone got impatient when you just "don't get it".
> I've seem the claim that you can't really use Haskell without [knowing category theory], here on HN, more than once
I've almost never come across this assertion; it's certainly not common in the community (or wasn't when I was learning Haskell). I can tell you it's certainly false: you can very well write Haskell without knowing or studying category theory.
I've only really ever seen monoids referred to in Haskell. If you actually read my comment, Haskell is not all FP (no PL is). It's not even a significant portion of FP. So just don't use Haskell, it's hardly the first FP language I would reach for and it's probably not the one you should either.
Also, any person willing to learn would be intrigued by the terminology, not reject it as something that's "gatekeeping". Such a defeatist attitude will not get you very far in a field as complex as this.
SQL DBs and the precise semantics of SQL are somewhat based on relational algebra, but SQL syntax is definitely not. It's also not using set theoretic terms in general, with the exception of UNION and INTERSECT.
It tells a lot how people go for common jokes to complain about a community. It's easy to fall for that if you never actually interacted with the people.
You just tried to badmouth whole community of FP programmers by taking serious a running gag, wow.
Quite frankly, if you don't understand that sentence then you are in no position to judge whether the concepts could be made more accessible. Sometimes the important question is not "could this be easier to learn?" but "is learning it worth the effort?".
