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SRFI 9 - Defining Record Types

SRFI 9 provides a way to define new record types. For each record type a predicate, a constructor, and field accessors and modifiers are defined. The new record types are distinct from all existing types.

The builtin record types in PLT is called structures, which in some circumstances are more flexible than srfi9-records, but are less portable across implementations.

The srfi documentation is available both at http://srfi.schemers.org/srfi-9/srfi-9.html and in the HelpDesk.

Requiring srfi 9

To use srfi9 in PLT Scheme use the following:

(require (lib "9.ss" "srfi"))

Example

> (require (lib "9.ss" "srfi"))
> (define-record-type :user
      (make-user name password)
      user?
      (name user-name set-user-name!)
      (password user-password set-user-password!))
> (define guest (make-user "Anonymous" "1234"))
> (user? guest)
#t
> (user-name guest)
"Anonymous"
> (set-user-name! guest "Guest")
> (user-name guest)
"Guest"