So in Rxjava terms a Monad is the lambda inside the map oper

Question

So in Rxjava terms a Monad is the lambda inside the map operator

rawtoast · Answer

No RxJava experience but The basic way to think about this is A Monad is an object that holds a another object and provides two methods `map` and `flatmap` There are additional rules Monad Laws etc but I wouldn t look into that until you are comfortable with using existing monads You could see Java s `Optional` as a monad It doesn t strictly meet the criteria as it violates the Monad Laws but as a beginner it may help to think of it as one

Andreas Sinz · Answer

< kenkyee> its the other way around Rx itself is the Framework Monad that the lambdas are executed in

tmg · Answer

`flatMap` is what Monad gives you besides some garantees if you respect the monad laws `map` comes from Funtors I guess you could call Monads a subclass of Functors

tmg · Answer

You can think of functors and monads as context or containers But it s best if you know the math behind it

pakoito · Answer

Monad is an object you can create that describes the way RxJava s Observables can be chained

pakoito · Answer

``` interface ObservableMonad fun lt A gt just a A Observable lt A gt = Observable just a fun lt A B gt flatMap obs Observable lt A gt f A gt Observable lt B gt Observable lt B gt = obs flatMap f ```

pakoito · Answer

and you can pass that as a parameter through your program describing how to chain Observables

pakoito · Answer

you can create them for lists and such

pakoito · Answer

``` interface ListMonad fun lt A gt just a A List lt A gt = listOf a fun lt A B gt flatMap list List lt A gt f A gt List lt B gt List lt B gt = list flatMap f ```

pakoito · Answer

so you can abstract over them and have special syntax

pakoito · Answer

or create whole programs that are polymorphic to these types and can be run using lists or observables or option and always behave the same because you only have those two operations and any other operation derived from it

pakoito · Answer

``` fun lt A B gt map list List lt A gt f A gt B List lt B gt = list flatMap a gt just f a ```

pakoito · Answer

so while `Observable` can be chained in a monadic way you need extra language support to use the Monad abstraction effectively

pakoito · Answer

for example with async await notation what the article does as let

pakoito · Answer

and arrow does like this <https arrow kt io docs integrations rx2 observable comprehensions>