List Modification (Guile Reference Manual)
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6.6.9.6 List Modification
The following procedures modify an existing list, either by changing
elements of the list, or by changing the list structure itself.
Scheme Procedure:
list-set!
list k val
C Function:
scm_list_set_x
(list, k, val)
Set the
th element of
list
to
val
Scheme Procedure:
list-cdr-set!
list k val
C Function:
scm_list_cdr_set_x
(list, k, val)
Set the
th cdr of
list
to
val
Scheme Procedure:
delq
item lst
C Function:
scm_delq
(item, lst)
Return a newly-created copy of
lst
with elements
eq?
to
item
removed. This procedure mirrors
memq
delq
compares elements of
lst
against
item
with
eq?
Scheme Procedure:
delv
item lst
C Function:
scm_delv
(item, lst)
Return a newly-created copy of
lst
with elements
eqv?
to
item
removed. This procedure mirrors
memv
delv
compares elements of
lst
against
item
with
eqv?
Scheme Procedure:
delete
item lst
C Function:
scm_delete
(item, lst)
Return a newly-created copy of
lst
with elements
equal?
to
item
removed. This procedure mirrors
member
delete
compares elements of
lst
against
item
with
equal?
See also SRFI-1 which has an extended
delete
Deleting
), and also an
lset-difference
which can delete
multiple
item
s in one call (
Set Operations on Lists
).
Scheme Procedure:
delq!
item lst
Scheme Procedure:
delv!
item lst
Scheme Procedure:
delete!
item lst
C Function:
scm_delq_x
(item, lst)
C Function:
scm_delv_x
(item, lst)
C Function:
scm_delete_x
(item, lst)
These procedures are destructive versions of
delq
delv
and
delete
: they modify the pointers in the existing
lst
rather than creating a new list. Caveat evaluator: Like other
destructive list functions, these functions cannot modify the binding of
lst
, and so cannot be used to delete the first element of
lst
destructively.
Scheme Procedure:
delq1!
item lst
C Function:
scm_delq1_x
(item, lst)
Like
delq!
, but only deletes the first occurrence of
item
from
lst
. Tests for equality using
eq?
. See also
delv1!
and
delete1!
Scheme Procedure:
delv1!
item lst
C Function:
scm_delv1_x
(item, lst)
Like
delv!
, but only deletes the first occurrence of
item
from
lst
. Tests for equality using
eqv?
. See also
delq1!
and
delete1!
Scheme Procedure:
delete1!
item lst
C Function:
scm_delete1_x
(item, lst)
Like
delete!
, but only deletes the first occurrence of
item
from
lst
. Tests for equality using
equal?
. See also
delq1!
and
delv1!
Scheme Procedure:
filter
pred lst
Scheme Procedure:
filter!
pred lst
Return a list containing all elements from
lst
which satisfy the
predicate
pred
. The elements in the result list have the same
order as in
lst
. The order in which
pred
is applied to
the list elements is not specified.
filter
does not change
lst
, but the result may share a
tail with it.
filter!
may modify
lst
to construct its
return.
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