(guile.info.gz) Sloppy Alist Functions

(guile.info.gz) Removing Alist Entries

 
 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.

Info Catalog

(guile.info.gz) Removing Alist Entries

(guile.info.gz) Association Lists

(guile.info.gz) Alist Example

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