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It seems to me like the { case ... => ... } syntax for partial functions require at least one case:
scala> val pf: PartialFunction[String, String] = { case "a" => "b" } pf: PartialFunction[String,String] = <function1> scala> val pf: PartialFunction[String, String] = { } <console>:5: error: type mismatch; found : Unit required: PartialFunction[String,String] val pf: PartialFunction[String, String] = { } ^ So, what's the best way to define an "empty" partial function? Is there a better way than "manually" overriding isDefinedAt and apply?
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When a function is not able to produce a return for every single variable input data given to it then that function is termed as Partial function. It can determine an output for a subset of some practicable inputs only. It can only be applied partially to the stated inputs.
andThen is just function composition. Given a function f val f: String => Int = s => s.length. andThen creates a new function which applies f followed by the argument function val g: Int => Int = i => i * 2 val h = f.andThen(g) h(x) is then g(f(x))
Map is a PartialFunction so you can do:
val undefined: PartialFunction[Any, Nothing] = Map.empty Since Scala 2.10 you can use:
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