Hi! I found the following question by @johangwbass...

# arrow

[alilosoft]

Hi! I found the following question by @johangwbasson on Gitter and I'm interested to know the answer but its not answered yet! so I forwarded it here:

Good day. I'm new to functional programming and the arrow library and was wondering if anybody can help me.

I was wondering how one handles resources like database pools or connections and how you pass them to a function. For instance: Let say I have an authenticate method:

fun authenticate(username: String, password: String): Either<Error, Token> {

// validation etc ..
val user = getUserByUsername(username)
}

fun getUserByUsername(username: String): Option<User> {

// JDBC Query for user
val rs = con.prepareStatement("SELECT * FROM user .....")
....
val user = mapRowToUser(rs) // etc
return Option.fromNullable(user)
}

My question is do I pass in the connection of database pool as a parameter like so:

fun authenticate(con: Connection, username: String, password: String) ....

fun getUserByUsername(con: Connection, username: String): Option<User> ...

What is the best practice when it comes to functional programming?

Also from what I have read and if my understanding is correct, this is impure and normally IO would be used?

fun getUserByUsername(username: String): IO<Option<User>>

Is this correct? Any help appreciated

PS: I think it could be better if a link to this channel is added to Arrow-kt.io web site home page.

[thanh]

Paco did answer this above 👆 https://kotlinlang.slack.com/archives/C5UPMM0A0/p1570615347003700

[alilosoft]

Sorry! I haven't seen it! 😏