' quote
The quote character is used to block LISP evaluation. When LISP evaluates a quoted thing the quote is "stripped off" and the expression following the quote is returnd.
? (+ 3 4) ; LISP evalutates the list
7
? '(+ 3 4) ; quote blocks evaluation
(+ 3 4) ; the quote is stripped off
? PI ; LISP evalutates the symbol
3.141592653589793
? ''PI ; the first quote is stripped off
'PI ; leaving the second quote intact
: colon
The colon introduces a special type of symbol called a keyword. A keyword is self-evaluating, that is, it is constant data.
? :woof-woof!
:WOOF-WOOF!
# cross
The cross character is used to introduce a special interpretation of the subsequent expression. Here are several examples:
#xFF00
Introduces digits in hexidecimal radix.
#(1 2 3)
Creates a vector (array) from a list of elements.
#'list
Returns the function associated with the symbol list. If no function is associated with the symbol LISP signals an error.
#|
Introduces a comment that lasts more than one line. A #| must be balanced by a terminating |#.
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