45 mzlib/struct

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41 | mzlib/ sendevent
42 | mzlib/ serialize
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44 | mzlib/ string
45 | mzlib/ struct
46 | mzlib/ stxparam
47 | mzlib/ surrogate
48 | mzlib/ tar
49 | mzlib/ thread
50 | mzlib/ trace
51 | mzlib/ traceld
52 | mzlib/ trait
53 | mzlib/ transcr
54 | mzlib/ unit
55 | mzlib/ unit-exptime
56 | mzlib/ unit200
57 | mzlib/ unitsig200
58 | mzlib/ zip
| Bibliography
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On this page:

copy-struct
define-struct/ properties
make->vector

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( require mzlib/struct)

( copy-struct struct-id struct-expr
(accessor-id field-expr) ...)

“Functional update” for structure instances. The result of evaluating struct-expr must be an instance of the structure type named by struct-id. The result of the copy-struct expression is a fresh instance of struct-id with the same field values as the result of struct-expr, except that the value for the field accessed by each accessor-id is replaced by the result of field-expr.

The result of struct-expr might be an instance of a sub-type of struct-id, but the result of the copy-struct expression is an immediate instance of struct-id. If struct-expr does not produce an instance of struct-id, the exn:fail:contract exception is raised.

If any accessor-id is not bound to an accessor of struct-id (according to the expansion-time information associated with struct-id), or if the same accessor-id is used twice, then a syntax error is raised.

( define-struct/properties id (field-id ...)
((prop-expr val-expr) ...)
maybe-inspector-expr)

maybe-inspector-expr

=

|  | | |  | expr

Like define-struct from mzscheme, but properties can be attached to the structure type. Each prop-expr should produce a structure-type property value, and each val-expr produces the corresponding value for the property.

Examples:

> ( define-struct/properties point (x y)
([ prop:custom-write ( lambda (p port write?)
( fprintf port "(~a, ~a)"
(point-x p)
(point-y p)))]))

> ( display (make-point 1 2))
(1, 2)

(make->vector struct-id)

Builds a function that accepts a structure type instance (matching struct-id) and provides a vector of the fields of the structure type instance.
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