String and List Operators

string-expression:
        expression // expression

list-formation-expression:
        expression // expression
        [ expression-listopt ]

expression-list:
        expression
        expression , expression-list

integer-expression:
        expression #

If the operands of // are of string or character type, the result will be a string which is the concatenation of the two operands. If the operands are of list type, the result will be a list which is the concatenation of the two operands. If either or both of the operands is @, the result will be @ (see pre-defined functions substr and sublist). The [] operator groups the values of the expressions into a list. The expression list is a list of expressions separated by commas. If the expression list is omitted the list returns a null list.