There is a lot of talk about monads these days. I have read a few articles / blog posts, but I can’t go far enough with their examples to fully grasp the concept. The reason is that monads are a functional language concept, and thus the examples are in languages I haven’t worked with (since … Read more
While explaining to someone what a type class X is I struggle to find good examples of data structures which are exactly X. So, I request examples for: A type constructor which is not a Functor. A type constructor which is a Functor, but not Applicative. A type constructor which is an Applicative, but is … Read more
In my humble opinion the answers to the famous question “What is a monad?”, especially the most voted ones, try to explain what is a monad without clearly explaining why monads are really necessary. Can they be explained as the solution to a problem? 8 Answers 8
I’ve seen the term Free Monad pop up every now and then for some time, but everyone just seems to use/discuss them without giving an explanation of what they are. So: what are free monads? (I’d say I’m familiar with monads and the Haskell basics, but have only a very rough knowledge of category theory.) … Read more
If I have an EnumeratorT and a corresponding IterateeT I can run them together: val en: EnumeratorT[String, Task] = EnumeratorT.enumList(List(“a”, “b”, “c”)) val it: IterateeT[String, Task, Int] = IterateeT.length (it &= en).run : Task[Int] If the enumerator monad is “bigger” than the iteratee monad, I can use up or, more generally, Hoist to “lift” the … Read more
Closed. This question needs to be more focused. It is not currently accepting answers. Closed 5 years ago. Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions. What is a good way to design/structure large functional programs, especially … Read more
Who first said the following? A monad is just a monoid in the category of endofunctors, what’s the problem? And on a less important note, is this true and if so could you give an explanation (hopefully one that can be understood by someone who doesn’t have much Haskell experience)? 5 s 5
In terms that an OOP programmer would understand (without any functional programming background), what is a monad? What problem does it solve and what are the most common places it’s used? Update To clarify the kind of understanding I was looking for, let’s say you were converting an FP application that had monads into an … Read more
Having briefly looked at Haskell recently, what would be a brief, succinct, practical explanation as to what a monad essentially is? I have found most explanations I’ve come across to be fairly inaccessible and lacking in practical detail. 4 46
