SML#: a new Standard ML family programming language(pllab.riec.tohoku.ac.jp)

    # type foo = { bar: int ; baz: string };;
    type foo = { bar : int; baz : string; }
    # let a = { bar = 42; baz = "hello" };;
    val a : foo = {bar = 42; baz = "hello"}
    # let b = {a with baz = "bye"};;
    val b : foo = {bar = 42; baz = "bye"}
    # a;;
    - : foo = {bar = 42; baz = "hello"}