gistfile1.scala

// Reader monad
val lifecycle = for {
  taxFeeIds <- forTrade // get the tax/fee ids for a trade
  taxFeeValues <- taxFeeCalculate // calculate tax fee values
  netAmount <- enrichTradeWith // enrich trade with net amount
}
yield((taxFeeIds ∘ taxFeeValues) ∘ netAmount)

// sample usage
val t1 = Map("account" -> "a-123", "instrument" -> "google", "refNo" -> "r-123", "market" -> "HongKong", "unitPrice" -> "12.25", "quantity" -> "200")
  val t2 = Map("account" -> "b-123", "instrument" -> "ibm", "refNo" -> "r-234", "market" -> "Singapore", "unitPrice" -> "15.25", "quantity" -> "400")

describe("trades") {
  it("should create and operate on multiple trades") {
    import Trades._

    val trd1 = makeTrade(t1)
    val trd2 = makeTrade(t2)

    (trd1 ∘ lifecycle) should equal(Some(Some(3307.5000)))
    (List(trd1, trd2) ∘∘ lifecycle) should equal (List(Some(Some(3307.5000)), Some(Some(8845.0000))))
  }
}