Keywords are similar to symbols.
The main difference is that keywords are self-evaluating
and therefore do not need to be quoted in expressions.
They are used mainly
for specifying keyword arguments.
[75] keyword = identifier:
A keyword is a single token; therefore, no whitespace is allowed
between the identifier and the :.
The : is not considered part of the name of the keyword.
8.5.5.1 Keyword Type Predicate
(keyword? obj)
Returns #t if obj is a keyword, and otherwise returns
#f.
8.5.5.2 Keyword to String Conversion
(keyword->string keyword)
Returns the name of keyword as a string.
(keyword->string Argentina:) "Argentina"
8.5.5.3 String to Keyword Conversion
(string->keyword string)
Returns the keyword whose name is string.
(string->keyword "foobar") foobar: