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Length: 1036 (0x40c)
Types: TextFile
Names: »ps8putget.scm«
└─⟦a0efdde77⟧ Bits:30001252 EUUGD11 Tape, 1987 Spring Conference Helsinki
└─⟦this⟧ »EUUGD11/gnu-31mar87/scheme/psets/ps8putget.scm«
;;; This is the file ps8-putget.scm
(define (make-table)
(let ((local-table (cons '*table* nil)))
(define (lookup key-1 key-2)
(let ((subtable (assq key-1 (cdr local-table))))
(if (null? subtable)
nil
(let ((pair (assq key-2 (cdr subtable))))
(if (null? pair)
nil
(cdr pair))))))
(define (insert! key-1 key-2 value)
(let ((subtable (assq key-1 (cdr local-table))))
(if (null? subtable)
(set-cdr! local-table
(cons (cons key-1
(cons (cons key-2 value) nil))
(cdr local-table)))
(let ((pair (assq key-2 (cdr subtable))))
(if (null? pair)
(set-cdr! subtable
(cons (cons key-2 value)
(cdr subtable)))
(set-cdr! pair value))))))
(define (dispatch m)
(cond ((eq? m 'lookup-proc) lookup)
((eq? m 'insert-proc!) insert!)
(else (error "Unknown operation -- TABLE" m))))
dispatch))
(define operation-table (make-table))
(define get (operation-table 'lookup-proc))
(define put (operation-table 'insert-proc!))