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caaaar caaadr ... caddar cadddr

caaaar caaadr ... caddar cadddr

type: function (subr) 
location: built-in
source file: xllist.c
Common LISP compatible: yes
supported on: all machines

SYNTAX

(caaaar <expr> )
(caaadr <expr> )
(caadar <expr> )
...
(caddar <expr> )
(cadddr <expr> )
        <expr>          -       a list or list expression

DESCRIPTION

The CAAAAR, CAAADR ... CADDAR, CADDDR functions go through the list expression and perform a sequence of CAR/CDR operations. The sequence of operations is performed from right to left. So CAADDR does a CDR on the expression, followed by a CDR, followed by a CAR, followed by another CAR. If at any point the list is NIL, NIL is returned. If at anypoint a CAR operation is performed on an atom (as opposed to a list) an error is reported - "error: BAD ARGUMENT".

EXAMPLES

(setq mylist '( ( (a b) (c d) (e f) )   ; make a 3-level list
                ( (g h) (i j) (k l) )
                ( (m n) (o p) (q r) )
                ( (s t) (u v) (w x) )
                ) )
(caaadr mylist)                         ; returns G
(caadar mylist)                         ; returns C
(cdadar mylist)                         ; returns (D)
(cadadr mylist)                         ; returns (I J)
(cdaddr mylist)                         ; returns ((O P) (Q R))
(cadddr mylist)                         ; returns ((S T) (U V) (W X))


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