chickadee » box

box

Documentation

Implements the box data type. A box is a cell containing a single, mutable or immutable, field. The boxed value maybe any Scheme type, including a variable or a location.

Two APIs are provided. A box API with CHICKEN concepts (box-core), and a SRFI 111 API (srfi-111).

Usage

(import box-core)

Box syntax

The lexical syntax of a box containing the scheme-object S* is #&S*.

Only mutable boxes can be recovered. An immutable, variable, or location box will lose identity when printed.

make-box

(make-box [INITIAL [IMMUTABLE? #f]]) -> boxprocedure

Returns a BOX with, optional, initial value INITIAL.

The BOX is mutable unless the IMMUTABLE? argument is #t.

An attempt to mutate an immutable box will signal an exception.

make-box-mutable

make-box-mutable #!optional INITIALprocedure

Returns a BOX with, optional, initial value INITIAL.

make-box-immutable

make-box-immutable INITIALprocedure

Returns a BOX with an initial value INITIAL.

An attempt to mutate an immutable box will signal an exception.

make-box-variable

(make-box-variable VARIABLE [IMMUTABLE? #f]) -> boxsyntax

Returns a boxed reference to the VARIABLE, which must be in lexical-scope.

The BOX is mutable unless the IMMUTABLE? argument is #t.

An attempt to mutate an immutable box will signal an exception.

make-box-location

(make-box-location TYPE INITIAL-VALUE [IMMUTABLE? #f]) -> boxsyntax

Returns a boxed reference to a location of TYPE and INITIAL-VALUE.

The BOX is mutable unless the IMMUTABLE? argument is #t.

An attempt to mutate an immutable box will signal an exception.

Unavailable in EVALuated source.

box?

box? OBJECTprocedure

Is OBJECT a BOX?

box-mutable?

box-mutable? OBJECTprocedure

Is OBJECT a mutable BOX?

box-immutable?

box-immutable? OBJECTprocedure

Is OBJECT an immutable BOX?

box-variable?

box-variable? OBJECTprocedure

Is OBJECT a boxed variable?

box-location?

box-location? OBJECTprocedure

Is OBJECT a boxed location?

box-set!

box-set! BOX OBJECTprocedure

Changes the boxed value of BOX to OBJECT. Will signal an exception for an immutable {{BOX}.

box-ref

box-ref BOXprocedure

Returns the boxed value of BOX.

box-location

(box-location BOX [WEAK? #f]) -> locationprocedure

Returns a LOCATION object for a boxed variable, location or locatable box. Signals an exception otherwise.

The locative is "strong" unless the WEAK? argument is #t. The WEAK? argument is ignored for boxed variables and locations.

The location of a boxed value or boxed location is the box. The location of a boxed variable is the same as (location (box-ref BOX)); currently the location of a symbol may not be taken.

See Locations.

box-swap!

box-swap! BOX FUNC #!optional OBJECT...procedure

Changes the boxed value of BOX to (FUNC <BOX-VALUE> OBJECT...). Will signal an exception for an immutable BOX. Returns the new value of BOX.

make-box-variable-closure

make-box-variable-closure IMMUTABLE? REF SETprocedure
IMMUTABLE?
boolean
REF
(-> *)
SET
(* -> void)

make-box-location-closure

make-box-location-closure IMMUTABLE? REF SET REFLOCprocedure
IMMUTABLE?
boolean
REF
(-> *)
SET
(* -> void)
REFLOC
(-> location)

SRFI-111

Usage

(import srfi-111)

box

box OBJECTprocedure

Returns a mutable BOX with initial value OBJECT.

immutable-box

immutable-box OBJECTprocedure

Returns a mutable BOX with value OBJECT.

box?

box? OBJECTprocedure

Is OBJECT a BOX?

unbox

unbox BOXprocedure

Returns the boxed value of BOX.

set-box!

set-box! BOX OBJECTprocedure

Changes the boxed value of BOX to OBJECT. Will signal an exception for an immutable {{BOX}.

Examples

#;1> (import box) ;(import box-core (srfi 111))
#;2> (define b (box 0))
#;3> b
#&0
#;4> (define (inc-box! bx) (set! (box-ref bx) (add1 (unbox bx))))
#;5> (inc-box! b)
#;6> (unbox b)
1
#;7> (box-swap! b add1)
2
#;8> (box-swap! b * 3)
6
#;9> (box-ref b)
6

Usage

(import box)

Requirements

check-errors

Bugs and Limitations

Author

Kon Lovett

Version history

3.2.4
srfi-111 bindings are procedure.
3.2.3
Fix type predicates.
3.2.2
srfi-111 provides box?.
3.2.1
Provide box-core module, box w/o srfi-111 bindings.
3.2.0
Provide srfi-111 module. Add make-box-mutable & make-box-immutable.
3.1.0
Add immutable-box.
3.0.0
CHICKEN 5 release.
2.4.0
Add make-box-variable-closure & make-box-location-closure.
2.3.3
Updated type information.
2.3.2
Added type information.
2.3.1
2.3.0
Added box-swap!. Fix for print of mutable box.
2.2.4
Bug fix for Chicken 4.6.3
2.2.3
2.2.2
2.2.1
2.1.0
Bug fix for box?. Added direct calls (only for use when the actual type is known.)
2.0.0
Port to hygienic Chicken. Reduced memory footprint for basic usage. Dropped keyword arguments.

License

Copyright (C) 2009-2018 Kon Lovett. All rights reserved.

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.

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