[lispm]

Ruby symbols are similar to keyword symbols in Common Lisp. There a keyword symbol is a symbol which evaluates to itself:

    CL-USER 69 > :a-keyword-symbol
    :A-KEYWORD-SYMBOL

Keywords with a similar name are identical:

    CL-USER 70 > (eq :a-keyword-symbol :a-keyword-symbol)
    T

One can't set keyword symbols to another value:

    CL-USER 71 > (setf :a-keyword-symbol 3)

    Error: Cannot setq :A-KEYWORD-SYMBOL -- it is a keyword.

They have certain features of normal symbols, like a property-list with keyword/value pairs.