Included with the
syntax-case files was structure.scm
which defines a macro
define-structure. Here is its
documentation from Gambit-4.0:
Record data types similar to Pascal records and C
structtypes can be defined using the
define-structurespecial form. The identifier name specifies the name of the new data type. The structure name is followed by k identifiers naming each field of the record. The
define-structureexpands into a set of definitions of the following procedures:
- `make-name' – A k argument procedure which constructs a new record from the value of its k fields.
- `name?' – A procedure which tests if its single argument is of the given record type.
- `name-field' – For each field, a procedure taking as its single argument a value of the given record type and returning the content of the corresponding field of the record.
- `name-field-set!' – For each field, a two argument procedure taking as its first argument a value of the given record type. The second argument gets assigned to the corresponding field of the record and the void object is returned.
Gambit record data types have a printed representation that includes the name of the type and the name and value of each field.
For example:> (require 'syntax-case) > (require 'repl) > (repl:top-level macro:eval) > (require 'structure) > (define-structure (point x y color)) > (define p (make-point 3 5 'red)) > p #<point #3 x: 3 y: 5 color: red> > (point-x p) 3 > (point-color p) red > (point-color-set! p 'black) > p #<point #3 x: 3 y: 5 color: black>