scala - Defining a ScalaCheck generator in terms of another Gen -

how define generator in produce random data fields of given block. following scaffolding code. need expression replace ???. expression should generate seq[field], field should generated using defined genfield function.

def blockgen(b: block): gen[block] = {     id <- b.blockid //use same blockid b     fields <- ??? //get type each field , call genfield } yield block(id, fields) 

adt

trait data {}  trait field extends data {   val name: string   val value: string }  case class stringfield(name: string, value: string) extends field case class numberfield(name: string, value: string) extends field case class block(blockid: field, fields: seq[field]) extends data 

generators

def fieldgen(fieldtype: field): gen[field] = {   {     f <-     fieldtype match {       case _: numberfield => numgen       case _: stringfield => strgen     }   } yield f }  val strgen: gen[stringfield] = {   name <- gen.identifier   value <- gen.alphastr } yield stringfield(name, value)  val numgen: gen[numberfield] = {   name <- gen.identifier   value <- gen.numstr } yield numberfield(name, value) 

sample block: myblock

val cx = new stringfield("blockid", "cx") val seg = stringfield("segmentation", "abc") val ver = numberfield("version", "1.0")  val myblock = block(cx, seq(seg, ver)) 

i believe you're looking gen.sequence.

also, id doesn't need come generator, since you're doing using particular value directly.

def blockgen(b: block): gen[block] =   {     fields <- gen.sequence[seq[field], field](b.fields.map(fieldgen))   } yield block(b.blockid, fields) 

by way, gen.sequence similar future.sequence , sequence in haskell.