Hello everyone,
Since I've discovered the concept of metaprogramming I've been quite interested
in Racket and its syntax extension capabilities.
While searching for a memoization syntax extension I found a macro whose
pattern extension remained unclear.
(define-syntax define/memoized
(syntax-rules ()
((_ (name . args) . body)
(define name (memoize (lambda args . body))))))
With the memoization function being defined as such:
(define (memoize f)
(local ([define table (make-hash)])
(lambda args
(dict-ref! table args (lambda () (apply f args))))))
What does the '.' mean in '(name . args)' and '. body'?
In a call like (define/memoized (foo x y z) (displayln "bar"))) I would imagine
that name would be matched to foo; (x y z) to args and body to (display ln
"bar") but why do we use the '. body' in the lambda expression at the end?
Thank you for your attention.
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