gistfile1.scala

/**
 * A quick debugging tip
 */

/**
 * If you have lots of definitions using the same type parameter names, like 'S'
 */ 
def beEmpty[S <: HasIsEmpty]: Matcher[S] = new EmptyMatcher()
def compose[S] (f: S => T) = new Matcher[S] { ... }

/**
 * You may get cryptic compiler messages: "could not find implicit value for parameter c: (B) => S"
 *
 * Just change (temporarily) the type variable to:
 */
def beEmpty[SHasIsEmpty <: HasIsEmpty]: Matcher[SHasIsEmpty] = new EmptyMatcher()

/**
 * And things start getting clearer!
 *
 * "could not find implicit value for parameter c: (B) => SHasIsEmpty"
 */