What happens when you pass the wrong kind of construct as a parameter?

  CLASS — instantiated objects with methods
  FUNCTION — callable units
  RECORD — data-only aggregates
  TRAIT — interface contracts
  SERVICE — HTTP endpoints

  doWork()
    -> action as Assessor of String
    ...

  doWork(MyClass())    // E50090 if MyClass is not an Assessor

defines module qa.types.parametergenus

  defines function

    <?-
      Function that accepts a predicate.
    -?>
    countMatching()
      ->
        items as List of String
        check as Predicate of String
      <- result as Integer: 0

      for item in items
        if check(item)
          result++

  defines program

    ParameterGenusDemo()
      stdout <- Stdout()

      names <- List() of String
      names += "Alice"
      names += "Bob"
      names += "Charlie"

      //Dynamic function matching Predicate of String
      minLength <- 4

      longCheck <- (minLen: minLength) is Predicate of String as pure function
        r: t? and length t >= minLen

      longCount <- countMatching(names, longCheck)
      stdout.println(`Long names: ${longCount}`)

      shortCheck <- (maxLen: minLength) is Predicate of String as pure function
        r: t? and length t < maxLen

      shortCount <- countMatching(names, shortCheck)
      stdout.println(`Short names: ${shortCount}`)

countMatching(names, stdout)

countMatching(names, longCheck)