Node:Records, Next:Structures, Previous:Vectors, Up:Compound Data Types
A record type is a first class object representing a user-defined data type. A record is an instance of a record type.
| record? obj | Scheme Procedure |
Return #t if obj is a record of any type and #f
otherwise.
Note that |
| make-record-type type-name field-names | Scheme Procedure |
| Return a record-type descriptor, a value representing a new data type disjoint from all others. The type-name argument must be a string, but is only used for debugging purposes (such as the printed representation of a record of the new type). The field-names argument is a list of symbols naming the fields of a record of the new type. It is an error if the list contains any duplicates. It is unspecified how record-type descriptors are represented. |
| record-constructor rtd [field-names] | Scheme Procedure |
Return a procedure for constructing new members of the type represented
by rtd. The returned procedure accepts exactly as many arguments
as there are symbols in the given list, field-names; these are
used, in order, as the initial values of those fields in a new record,
which is returned by the constructor procedure. The values of any
fields not named in that list are unspecified. The field-names
argument defaults to the list of field names in the call to
make-record-type that created the type represented by rtd;
if the field-names argument is provided, it is an error if it
contains any duplicates or any symbols not in the default list.
|
| record-predicate rtd | Scheme Procedure |
| Return a procedure for testing membership in the type represented by rtd. The returned procedure accepts exactly one argument and returns a true value if the argument is a member of the indicated record type; it returns a false value otherwise. |
| record-accessor rtd field-name | Scheme Procedure |
Return a procedure for reading the value of a particular field of a
member of the type represented by rtd. The returned procedure
accepts exactly one argument which must be a record of the appropriate
type; it returns the current value of the field named by the symbol
field-name in that record. The symbol field-name must be a
member of the list of field-names in the call to make-record-type
that created the type represented by rtd.
|
| record-modifier rtd field-name | Scheme Procedure |
Return a procedure for writing the value of a particular field of a
member of the type represented by rtd. The returned procedure
accepts exactly two arguments: first, a record of the appropriate type,
and second, an arbitrary Scheme value; it modifies the field named by
the symbol field-name in that record to contain the given value.
The returned value of the modifier procedure is unspecified. The symbol
field-name must be a member of the list of field-names in the call
to make-record-type that created the type represented by
rtd.
|
| record-type-descriptor record | Scheme Procedure |
Return a record-type descriptor representing the type of the given
record. That is, for example, if the returned descriptor were passed to
record-predicate, the resulting predicate would return a true
value when passed the given record. Note that it is not necessarily the
case that the returned descriptor is the one that was passed to
record-constructor in the call that created the constructor
procedure that created the given record.
|
| record-type-name rtd | Scheme Procedure |
Return the type-name associated with the type represented by rtd. The
returned value is eqv? to the type-name argument given in
the call to make-record-type that created the type represented by
rtd.
|
| record-type-fields rtd | Scheme Procedure |
Return a list of the symbols naming the fields in members of the type
represented by rtd. The returned value is equal? to the
field-names argument given in the call to make-record-type that
created the type represented by rtd.
|