— special form: define-structure (name field...)

Record data types similar to Pascal records and C struct types can be defined using the define-structure special 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-structure expands 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 'syntax-case)
          > (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
          > (set-point-color! p 'black)
          > p
          #<point #3 x: 3 y: 5 color: black>