Scala doesn't have lazy evaluation of function arguments, it's got call-by-name. The difference is that lazy evaluation caches the value an argument evaluates to the first time it is needed, so it's evaluated at most once, whereas call-by-name simply passes the parameter unevaluated and the result of evaluation is not cached, so might be computed more than once.

Consider this Scala program

     object Main extends {

       def tryit [ T ] ( block : => T ) : Unit = {
         println ( "----- Running 1st block -----" )
         block
         println ( "----- Running 2nd block -----" )
         block
         println ( "--------- Finished ----------" ) }

       def main ( args : Array [ String ] ) {
         var i = -1
         tryit ( { i += 1; println ( s"i = $i" ) } ) }

     }