More exercises on lists

    1. Write down some examples of expressions denoting:
        a list of numbers
        a list of words
        a list of numbers and words
        a list of lists of words
        a list of lists of numbers

    2. What is denoted by each of the following:

        hd( [ once upon a time ] )
        last( [ mary had a little lamb ] )
        hd( [ [mary had] [a little lamb] ] )
        rev( [ mary had a little lamb ] )
        last( hd( [ [ mary had ] [ a little lamb ] ] ) )
        delete( "cat", [mouse pig cat dog cat] )
        delete( "cat", [mouse pig cat dog cat], 1 )


    3. What does oneof do?
        NB. Your answer should take the form:
        ONEOF is a procedure which takes one argument (or one input
        item) and produces one result. The argument must be a ....
        The result will be .....

    4. What does delete do?
        (I.e. how many arguments does it take? What sorts of things
        can they be? How many results does it produce? How is the
        result related to the arguments?)

    5. What do the following denote:

        delete(3, rev([ 1 2 3 4 5]) )

        rev( delete( "little", [mary had a little lamb] ) )