Bigloo supports two kinds of enumerated types: the 
structures and
the 
records. They offer similar facilities. Structures were 
pre-existing to records and they are maintained mainly for backward
compatiblity. Recors are compliant with the Scheme request for 
implementation 9.
There is, in Bigloo, a new class of objects: 
structures, which are equivalent to C 
struct.
| 
This form defines a structure with name| define-struct name field... | bigloo syntax |  name, which is a symbol,
having fieldsfield... which are symbols or lists, each
list being composed of a symbol and a default value. This form creates
several functions: creator, predicate, accessor and assigner functions. The
name of each function is built in the following way:FunctionCreator: make-namePredicate: name?Accessor: name-fieldAssigner: name-field-set!
 make-accepts optional arguments. If a
single argument is provided, all the slots of the created structures
are filled with it. If more than one argument is passed, the various
values are used to initialize the corresponding structure slots. The
creator namednamenameaccepts as many arguments as the number of
slots of the structure. This function allocates a structure and fills
each of its slots with its corresponding argument.
 If a structure is created using
 make-and no initialization
value is provided, the slot default values (when provided) are used
to initialize the new structure. For instance, the execution of the program:name
 
 
| (define-struct pt1 a b)
(define-struct pt2 (h 4) (g 6))
 (make-pt1)
   => #{PT1 () ()}
(make-pt1 5)
   => #{PT1 5 5}
(make-pt2)
   => #{PT2 4 6}
(make-pt2 5)
   => #{PT2 5 5}
 |  | 
| 
Returns| struct? obj | bigloo procedure |  #tif and only ifobjis a structure. | 
 
 
Bigloo supports records has specified by SRFI-9. This section is a copy
of the SRFI-9 specification by Richard Kelsey. This SRFI describes
syntax for creating new data types, called record types.  A predicate,
constructor, and field accessors and modifiers are defined for each
record type.  Each new record type is distinct from all existing types,
including other record types and Scheme's predefined types.
| 
The syntax of a record-type definition is:| define-record-type expression... | syntax |  
 
 
| <record-type-definition> ==> (define-record-type<type-name>
                                         (<constructor-name> <field-tag> ...)
                                         <predicate-name>
                                         <field-spec> ...)
<field-spec>             ==> (<field-tag> <accessor-name>)
                           | (<field-tag> <accessor-name> <modifier-name>)
<field-tag>              ==> <identifier>
<accessor-name>          ==> <identifier>
<predicate-name>         ==> <identifier>
<modifier-name>          ==> <identifier>
<type-name>              ==> <identifier> |  Define-record-typeis generative: each use creates a new record
type that is distinct from all existing types, including other record
types and Scheme's predefined types. Record-type definitions may only
occur at top-level (there are two possible semantics for `internal'
record-type definitions, generative and nongenerative, and no consensus
as to which is better).
 an instance of
 define-record-typeis equivalent to the following
definitions:
 
 
 Records are disjoint from the types listed in Section 4.2 of R5RS.<type-name>is bound to a representation of the record type itself. Operations on
record types, such as defining print methods, reflection, etc. are left
to other SRFIs.
 
<constructor-name>is bound to a procedure that takes as many arguments as the
re are<field-tag>s in the(<constructor-name> ...)subform 
and returns a new<type-name>record. Fields whose tags are listed 
with<constructor-name>have the corresponding argument as their 
initial value. The initial values of all other fields are unspecified.
 
<predicate-name>is a predicate that returns#twhen given a value returned by<constructor-name>and#ffor everything else.
 
Each <accessor-name>is a procedure that takes a record of 
type<type-name>and returns the current value of the corresponding 
field. It is an error to pass an accessor a value which is not a record 
of the appropriate type.
 
Each <modifier-name>is a procedure that takes a record of 
type<type-name>and a value which becomes the new value of the 
corresponding field; an unspecified value is returned. It is an error 
to pass a modifier a first argument which is not a record of the appropriate 
type.
 
 Seting the value of any of these identifiers has no effect on the
behavior of any of their original values.
 
 The following
 
 
 
defines| (define-record-type pare
    (kons x y)
    pare?
    (x kar set-kar!)
    (y kdr))
 |  konsto be a constructor,karandkdrto be 
accessors,set-kar!to be a modifier, andpare?to be a 
predicate forpares.
 
 
|   (pare? (kons 1 2))        => #t
  (pare? (cons 1 2))        => #f
  (kar (kons 1 2))          => 1
  (kdr (kons 1 2))          => 2
  (let ((k (kons 1 2)))
    (set-kar! k 3)
    (kar k))                => 3
 |  |