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(SRFI-1 Association Lists): In alist-delete and

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alist-delete!, note argument order for the equality calls per SRFI-1
spec.
This commit is contained in:
Kevin Ryde 2003-08-29 23:30:00 +00:00
parent d61d8580a5
commit bd35f1f07c
1 changed files with 13 additions and 5 deletions
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18
doc/ref/srfi-modules.texi
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@ -774,12 +774,20 @@ spine of the list as well as the pairs are copied.
@deffn {Scheme Procedure} alist-delete key alist [=] @deffn {Scheme Procedure} alist-delete key alist [=]
@deffnx {Scheme Procedure} alist-delete! key alist [=] @deffnx {Scheme Procedure} alist-delete! key alist [=]
Return a list containing the pairs of @var{alist}, but without the Return a list containing the elements of @var{alist} but with those
pairs whose @sc{cars} are equal to @var{key}. Equality is determined elements whose keys are equal to @var{key} deleted. The returned
by @var{=}, which defaults to @code{equal?} if not given. elements will be in the same order as they were in @var{alist}.
@code{alist-delete!} is allowed, but not required to modify the Equality is determined by the @var{=} predicate, or @code{equal?} if
structure of the list @var{alist} in order to produce the result. not given. The order in which elements are tested is unspecified, but
each equality call is made @code{(= key alistkey)}, ie. the given
@var{key} parameter is first and the key from @var{alist} second.
This means for instance all associations with a key greater than 5 can
be removed with @code{(alist-delete 5 alist <)}.
@code{alist-delete} does not modify @var{alist}, but the return might
share a common tail with @var{alist}. @code{alist-delete!} may modify
the list structure of @var{alist} to construct its return.
@end deffn @end deffn