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A record type is a first class object representing a user-defined data type. A record is an instance of a record type.
Note that in many ways, this interface is too low-level for every-day use. Most uses of records are better served by SRFI-9 records. See SRFI-9 Records.
Return #t if obj is a record of any type and #f
otherwise.
Note that record? may be true of any Scheme value; there is no
promise that records are disjoint with other Scheme types.
Create and return a new record-type descriptor.
type-name is a string naming the type. Currently it’s only used in the printed representation of records, and in diagnostics. field-names is a list of symbols naming the fields of a record of the type. Duplicates are not allowed among these symbols.
(make-record-type "employee" '(name age salary))
The optional print argument is a function used by
display, write, etc, for printing a record of the new
type. It’s called as (print record port) and should look
at record and write to port.
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.
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.
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.
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.
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.
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.
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.
Next: Structures, Previous: SRFI-9 Records, Up: Compound Data Types [Contents][Index]