"Honestly, I don't understand how someone can write in a functional language and not know these concepts"
I totally support @jowiar on this. I have about 4 years of experience of writing in Scala and I don't think there was even one day when I needed to know monoids, functors and monads :) I have a blurry idea what monads are about but, honestly, I could have done without it.
In my work, when I make code reviews, I emphasize simplicity and readability. And I wouldn't want to see anyone of my coworkers using scalaz or a similar library. It's not true that if you don't like it you don't have to use it. If in a team of developers one person starts to use them, it's eventually going to propagate: After some time someone will have to write code accessing the code written with scalaz, then another person will have write something using that, and so on, and so on. And then it is enough that an experienced developer goes to another project and a new one takes her place (and this is not a rare situation - it's just something that happens every few months). And then the new developer looks at the code and is unable to say what is happening there without learning what all those cryptic operators and weird classes names are about.
The strength of a programming language lies not in how few times you have to push keyboard keys in order to write an application. It lies in how practical it is for a team to collaborate using it. If a team decides that the language is hard to read and hard to learn, they will search for another one. If enough teams decide that, the language dies.
I totally support @jowiar on this. I have about 4 years of experience of writing in Scala and I don't think there was even one day when I needed to know monoids, functors and monads :) I have a blurry idea what monads are about but, honestly, I could have done without it.
In my work, when I make code reviews, I emphasize simplicity and readability. And I wouldn't want to see anyone of my coworkers using scalaz or a similar library. It's not true that if you don't like it you don't have to use it. If in a team of developers one person starts to use them, it's eventually going to propagate: After some time someone will have to write code accessing the code written with scalaz, then another person will have write something using that, and so on, and so on. And then it is enough that an experienced developer goes to another project and a new one takes her place (and this is not a rare situation - it's just something that happens every few months). And then the new developer looks at the code and is unable to say what is happening there without learning what all those cryptic operators and weird classes names are about.
The strength of a programming language lies not in how few times you have to push keyboard keys in order to write an application. It lies in how practical it is for a team to collaborate using it. If a team decides that the language is hard to read and hard to learn, they will search for another one. If enough teams decide that, the language dies.