scala > ER ( 1 ) res0 : ErrRef [ Int ] = ErrRef @ a96606 scala > res0 ( ) res1 : Int = 1 scala > res0 ( ) = 3 scala > res0 ( ) res3 : Int = 3 scala > res0 ( ) = { println ( "Hello world" ) ; 3 } Hello world scala > res0 ( ) res5 : Int = 3 scala > res0 ( ) = error ( "Lets see what happens here..." ) scala > res0 ( ) java. lang . RuntimeException : Lets see what happens here... at ErrRef. apply ( RefExcept. scala : 11 ) at . < init > ( < console >: 6 ) at . < clinit > ( < console > ) at RequestResult$. < init > ( < console >: 3 ) at RequestResult$. < clinit > ( < console > ) at RequestResult$result ( < console > ) at sun. reflect . NativeMethodAccessorImpl . invoke0 ( Native Method ) at sun. reflect . NativeMethodAccessorImpl . invoke ( NativeMethodAcc... scala > res0 ( ) = throw new IllegalArgumentException ( "Go away" ) scala > res0 ( ) java. lang . IllegalArgumentException : Go away at ErrRef. apply ( RefExcept. scala : 11 ) at . < init > ( < console >: 6 ) at . < clinit > ( < console > ) at RequestResult$. < init > ( < console >: 3 ) at RequestResult$. < clinit > ( < console > ) at RequestResult$result ( < console > ) at sun. reflect . NativeMethodAccessorImpl . invoke0 ( Native Method ) at sun. reflect . NativeMethodAccessorImpl . invoke ( NativeMethodAccessorI...