list-utils - The CHICKEN Scheme wiki

Documentation

Usage

(import (list-utils basic))

length=0?

[syntax] (length=0? LIST) -> boolean

List of length zero? (Just null?.)

length=1?

[syntax] (length=1? LIST) -> boolean

List of length one?

length>1?

[syntax] (length>1? LIST) -> boolean

List of length greater than one?

length=2?

[syntax] (length=2? LIST) -> boolean

List of length two?

ensure-list

[syntax] (ensure-list OBJ) -> list

Returns a list, either the list OBJ or (list OBJ).

not-null?

[syntax] (not-null? LIST) -> (or list boolean)

Returns #f if the given LIST is empty, and LIST otherwise.

pair-ref

[procedure] (pair-ref LIST IDX) -> list

Returns the IDXth pair of LIST.

list-set!

[procedure] (list-set! LIST IDX OBJ) -> list

Replaces the car the (pair-ref LIST IDX) with OBJ.

list-copy*

[procedure] (list-copy* LIST START END FILL) -> list

Returns a copy of LIST, from START until END, where END maybe > (length LIST)). In which case FILL is used.

make-list/as

[procedure] (make-list/as OBJ) --> (#!optional (or integer list) -> (or OBJ (list-of OBJ)))

Returns a procedure producing a list of the supplied object OBJ, of length equal to the integer or the (length list).

(define falses (make-list/as #f))
(falses '(1 2)) ;=> (#f #f)
(falses 1)      ;=> (#f)

Usage

(import (list-utils operations))

skip+

[procedure] (skip+ LIST COUNT) -> (list integer)

Returns 2 values, the COUNT pair from LIST, and the remaining count. The remaining count will be zero when end-of-list reached.

COUNT is a natural fixnum.

(skip+ '(1 2) 3) ;=> '() 1
(skip+ '(1 2 3) 3) ;=> '() 0
(skip+ '(1 2 3 4) 3) ;=> '(4) 0

list-unique/duplicates

[procedure] (list-unique/duplicates LIST [EQAL?]) -> list list

Returns 2 values, the sorted list w/o duplicates & the list of duplicates.

EQAL?: a b -> * ; the equality predicate.

list-unique

[procedure] (list-unique LIST [EQAL?]) -> list

Returns the sorted list w/o duplicates.

EQAL?: a b -> * ; the equality predicate.

split-at+

[procedure] (split-at+ LIST COUNT [PADS]) -> (list list)

Returns 2 values, the leading COUNT elements from LIST as a new list, and the remaining elements from LIST. Should there be fewer than COUNT elements available padding is attempted.

Padding is performed by trying to complete the remaining elements from the list PADS.

COUNT is a natural fixnum. PADS is a list or #f. Default is '().

A negative COUNT is treated as 0.

When PADS is #f then an incomplete leading sublist is treated as '(). The very odd treatment of PADS = #f can safely be ignored since this is not the default behavior.

(split-at+ '(1 2 3) 3) ;=> '(1 2 3) '()
(split-at+ '(1 2 3) 2) ;=> '(1 2) '(3)
(split-at+ '(1 2 3) 4) ;=> '(1 2 3) '()
(split-at+ '(1 2 3) 4 #f) ;=> '() '()

section

[procedure] (section LIST SIZE [[STEP] PADS]) -> list

Returns a list of list, built by taking SIZE elements from LIST every STEP elements. When too few elements remain to complete a section padding is performed.

SIZE is a positive fixnum. STEP is a positive fixnum. Default is SIZE. PADS is a list or #f. Default is '().

When PADS is #f then any incomplete trailing section is dropped. The very odd treatment of PADS = #f can safely be ignored since this is not the default behavior.

(section '(1 2) 3 3 '(3 4 5)) ;=> ((1 2 3))
(section '(1 2 3) 2 1 '(3 4 5)) ;=> ((1 2) (2 3))
(section '(1 2 3) 2 2 '(4 5)) ;=> ((1 2) (3 4))
(section '(1 2 3) 2 2) ;=> ((1 2) (3))

shift!

[procedure] (shift! LIST [DEFAULT]) -> *

Returns the first element of LIST, or DEFAULT when LIST is null.

The car and cdr of the first pair of LIST are set to the corresponding element of the second pair.

Like a stack-pop.

unshift!

[procedure] (unshift! OBJ LIST) -> list

The car of the first pair of LIST is set to OBJ. The cdr of the first pair of LIST is set to LIST.

Like a stack-push.

shift!/set

[syntax] (shift!/set VARIABLE [WHEN-EMPTY])

Like shift! but assigns the VARIABLE '() after shifting from a list of length 1.

WHEN-EMPTY, which defaults to #f, is returned when the list bound to VARIABLE is empty.

andmap

[procedure] (andmap FUNC LIST...) -> boolean

The arity of the function FUNC must be the length of LIST....

(and (FUNC (car LIST)...) (andmap FUNC (cdr LIST)...)).

ormap

[procedure] (ormap FUNC LIST...) -> boolean

The arity of the function FUNC must be the length of LIST....

(or (FUNC (car LIST)...) (ormap FUNC (cdr LIST)...)).

ensure-flat-list

[procedure] (ensure-flat-list OBJ) -> list

Works like (list-flatten (ensure-list OBJ)).

list-flatten

[procedure] (list-flatten LIST) -> list

Returns a flattened LIST.

tree-fold

[procedure] (tree-fold FUNC SEED LIST) -> any

Returns result of FUNC, recursively, applied to each atom of the tree, from the initial SEED.

fold-right*

[procedure] (fold-right* FUNC LIST SEEDS...) -> * ...

Returns result of FUNC, applied to each element of the LIST, and the SEEDS....

FUNC: (* #!rest * -> . *) ;
LIST: list ; list to traverse
SEEDS...: * ... ; zero or more objects to initially seed the FUNC

Usage

(import (list-utils alist))

plist?

[procedure] (alist? OBJ) -> boolean
[procedure] (plist? OBJ) -> boolean

Is OBJ a list of the association or property kind?

alist-delete-first

[syntax] (alist-delete-first KEY ALIST [TEST?])

Returns (alist-delete-with-count KEY ALIST [TEST?] 1).

alist-delete-first!

[syntax] (alist-delete-first! KEY ALIST [TEST?])

Destructive version of alist-delete-first.

assoc-def

[syntax] (assoc-def KEY ALIST [TEST] [NOT-FOUND])

The assoc procedure with an optional test and default value.

Error signaling version of assoc. When the KEY is not found and a NOT-FOUND value is not supplied an error is invoked.

assv-def

[syntax] (assv-def KEY ALIST [NOT-FOUND])

The assv procedure with a default value.

Error signaling version of assv. When the KEY is not found and a NOT-FOUND value is not supplied an error is invoked.

assq-def

[syntax] (assq-def KEY ALIST [NOT-FOUND])

The assq procedure with a default value.

Error signaling version of assq. When the KEY is not found and a NOT-FOUND value is not supplied an error is invoked.

alist-inverse-ref

[procedure] (alist-inverse-ref VALUE ALIST [TEST? [NOT-FOUND]])

Returns the first key associated with VALUE in the ALIST using the TEST? predicate, else NOT-FOUND.

TEST? is eqv? and NOT-FOUND is #f.

alist-delete-duplicates

[procedure] (alist-delete-duplicates KEY ALIST [TEST? [COUNT]]) -> alist

Deletes the first COUNT associations from alist ALIST with the given key KEY, using key-comparison procedure TEST?. The dynamic order in which the various applications of equality are made is from the alist head to the tail.

Returns a new alist. The alist is not disordered - elements that appear in the result alist occur in the same order as they occur in the argument alist.

The test procedure is used to compare the element keys, key[i: 0 <= i < (length ALIST)', of the alist's entries to the key parameter in this way: (TEST? KEY key[i]).

COUNT defaults to unlimited, & TEST? defaults to eqv?.

alist-delete-duplicates!

[procedure] (alist-delete-duplicates! KEY ALIST [TEST? [COUNT]]) -> alist

Destructive version of alist-delete-with-count.

alist-delete-first and alist-delete-first! are also available.

sort-alist

[procedure] (sort-alist ALIST [LESSP]) -> alist

ALIST: (list-of pair) ; less-than procedure, default <.
LESSP: (* * --> boolean) ; less-than procedure, default <.

sort-alist!

[procedure] (sort-alist! ALIST [LESSP]) -> alist

ALIST: (list-of pair) ; less-than procedure, default <.
LESSP: (* * --> boolean) ; less-than procedure, default <.

unzip-alist

[procedure] (unzip-alist ALIST)

Returns 2 values, a list of the keys & a list of the values from the ALIST.

zip-alist

[procedure] (zip-alist KEYS VALUES)

Returns an association list with elements from the corresponding items of KEYS and VALUES.

plist->alist

[procedure] (plist->alist PLIST) -> list

Returns the association-list form of PLIST.

alist->plist

[procedure] (alist->plist ALIST) -> list

Returns the property-list form of ALIST.

list-utils sample

Usage

(import (list-utils sample))

list-randoms

[procedure] (list-randoms CNT [END [LOW [DUPS?]]]) -> (list-of integer)

Returns list of random integers in the open-interval [LOW END).

CNT: fixnum ; length of result list.
END: integer ; maximum value + 1, default most-positive-fixnum.
LOW: integer ; minimum value, default 0.
DUPS?: boolean ; allow duplicates, default #f.

list-random-sample

[procedure] (list-random-sample LIST [CNT]) -> list

Returns list of elements randomly sampled from LIST.

CNT: fixnum ; length of result list, default is random in [0 (- (length LIST) 1)].

list-cyclic-sample

[procedure] (list-cyclic-sample LIST [CNT]) -> list

Returns list of elements, sampled every CNT elements, from LIST.

Every element i in [0 length(LIST)-1] where i modulo CNT = 0; so first element always included.

CNT: fixnum ; cycle length, default is 7.

list-utils comma)

Usage

(import (list-utils comma))

list->comma-string

[procedure] (list->comma-string LIST [EMPTY? [COMMA]]) -> string

Returns list elements, as strings, joined with COMMA.

EMPTY?: boolean ; allow empties? default #f.
COMMA: string ; comma string. default ", ".

comma-string->list

[procedure] (comma-string->list STR [TRIM]) -> (list-of string)

Returns STR elements, joined with #\,, as a list.

STR: string ; simple comma list.
TRIM: (string -> string) ; process list elements. default string-trim-whitespace-both.

list-comma-join

[procedure] (list-comma-join . REST) -> string

Returns (list->comma-string REST.

make-comma-string

[procedure] (make-comma-string LEN [STR]) -> string

Returns a comma-string of length LEN and element STR, default "?".

Requirements

utf8 srfi-1 check-errors

test test-utils

Author

Kon Lovett

Repository

This egg is hosted on the CHICKEN Subversion repository:

https://anonymous@code.call-cc.org/svn/chicken-eggs/release/5/list-utils

If you want to check out the source code repository of this egg and you are not familiar with Subversion, see this page.

Version history

2.8.0: Move folds & flattens from basic to operations.
2.7.2: Export plist?. Weaken alist? & plist?.
2.7.1: Update list-flatten.
2.7.0: Fix signatures, add tree-fold.
2.6.0: Split into (list-utils basic), (list-utils alist), and (list-utils operations) w/ (list-utils) as omnibus. Add make-list/as.
2.5.1: Copy tail.
2.5.0: Add (list-utils sample), & (list-utils comma).
2.4.2: New test-runner, add .
2.4.1: Use check-errors.
2.4.0: Add sort-alist, sort-alist!, list-randoms, & list-sample.
2.3.0: Add list-flatten & ensure-flat-list. Add comma-list-utils.
2.2.0: Add list-unique & list-unique/duplicates.
2.1.1: Fix split-at+ optional argument.
2.1.0: Deprecate alist-delete/count & alist-delete!/count.
2.0.1: Fix egg category.
2.0.0: CHICKEN 5 release.
1.4.0: Add alist-delete-duplicates(!), pair-ref, list-set!, list-copy*. Deperecate alist-delete-with/for-count(!).
1.3.0: Add alist-delete-with-count & alist-delete-with-count!.
1.2.0: Add alist-delete-for-count & alist-delete-for-count!.
1.1.2: .
1.1.1: Fix for ticket #630
1.1.0: Added skip+, split-at+, and section.
1.0.0: Hello,

License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the Software), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ASIS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.