Guile Reference Manual
22.7.2.5 Sloppy Alist Functions
sloppy-assq, sloppy-assv and sloppy-assoc behave
like the corresponding non-sloppy- procedures, except that they
return #f when the specified association list is not well-formed,
where the non-sloppy- versions would signal an error.
Specifically, there are two conditions for which the non-sloppy-
procedures signal an error, which the sloppy- procedures handle
instead by returning #f. Firstly, if the specified alist as a
whole is not a proper list:
| | (assoc "mary" '((1 . 2) ("key" . "door") . "open sesame"))
=>
ERROR: In procedure assoc in expression (assoc "mary" (quote #)):
ERROR: Wrong type argument in position 2 (expecting NULLP): "open sesame"
ABORT: (wrong-type-arg)
(sloppy-assoc "mary" '((1 . 2) ("key" . "door") . "open sesame"))
=>
#f
|
Secondly, if one of the entries in the specified alist is not a pair:
| | (assoc 2 '((1 . 1) 2 (3 . 9)))
=>
ERROR: In procedure assoc in expression (assoc 2 (quote #)):
ERROR: Wrong type argument in position 2 (expecting CONSP): 2
ABORT: (wrong-type-arg)
(sloppy-assoc 2 '((1 . 1) 2 (3 . 9)))
=>
#f
|
Unless you are explicitly working with badly formed association lists,
it is much safer to use the non-sloppy- procedures, because they
help to highlight coding and data errors that the sloppy-
versions would silently cover up.
- Scheme Procedure: sloppy-assq key alist
-
- C Function: scm_sloppy_assq (key, alist)
- Behaves like
assq but does not do any error checking.
Recommended only for use in Guile internals.
- Scheme Procedure: sloppy-assv key alist
-
- C Function: scm_sloppy_assv (key, alist)
- Behaves like
assv but does not do any error checking.
Recommended only for use in Guile internals.
- Scheme Procedure: sloppy-assoc key alist
-
- C Function: scm_sloppy_assoc (key, alist)
- Behaves like
assoc but does not do any error checking.
Recommended only for use in Guile internals.
