functional programming - Accessing Previous output while operator chaining in Scala -

how access resulting output value perform upcoming operation example:

scala> list(1,4,3,4,4,5,6,7) res0: list[int] = list(1, 4, 3, 4, 4, 5, 6, 7)  scala> res0.removeduplicates.slice(0, ???.size -2) 

in above line, need perform slice operation after removing duplicates. this, how access output of .removeduplicate(), can use find size slice operation.

i need perform in single step. not in multiple steps like:

scala> res0.removeduplicates res1: list[int] = list(1, 4, 3, 5, 6, 7)  scala> res1.slice(0, res1.size -2) res2: list[int] = list(1, 4, 3, 5) 

i want access intermediate results in final operation. removeduplicates() example.

list.op1().op2().op3().finalop() here want access: output of op1,op2,op3 in finalop

wrapping into option may 1 option (no pun intended):

val finalresult = some(foo).map { foo =>    foo.op1(foo.stuff) }.map { foo =>    foo.op2(foo.stuff) }.map { foo =>    foo.op3(foo.stuff) }.get.finalop 

you can make wrapping part implicit make little nicer:

object tapper {   implicit class tapped[t] extends anyval(val v: t) {      def tap[r](f: t => r) = f(v)   } }  import tapper._ val finalresult = foo  .tap(f => f.op1(f.stuff))  .tap(f => f.op2(f.stuff))  .tap(f => f.finalop(f.stuff))