scala - Transform and flatten List of disjunctions - 


case class errs(errors: list[err])  case class err(exceptionmessage: string, custommessage: string, statuscode: int, extrainfo: option[string] = none)

one of functions returning val result = list[\/[errs, boolean]]

in order transform/sequence , flatten result following passes done

val finalres: \/[errs, boolean] = result.map(_.swap).sequenceu.map(x => errs(x.map(_.errors).flatten)).swap

this looks inelegant , performance intensive (given number of passes has via multiple map calls etc)

is there combinator in scalaz can make more elegant less number of passes or demands writing custom function?

firstly, use traverseu, suggested travis brown.

after that, call map followed call flatten can written flatmap.

val finalres: \/[errs, boolean] = result.traverseu(_.swap).map(x => errs(x.flatmap(_.errors))).swap

moreover, may consider using type alias errs.

type errs = list[err]

so, code simpler (less boxing/unboxing) :

val finalres: \/[errs, boolean] = result.traverseu(_.swap).map(_.flatten).swap

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