Racket's OO system has the 'augment' family of functionality that allows
you to change how a function works. I'm wondering if there's a way to do
something similar in functional Racket. For example, when I was working in
Perl I used to be able to do something like this Racket pseudocode:
> (define (greet name)
(println (string-append "Hi, " name)))
> (greet "bob")
"Hi, bob!"
> (greet 'bob)
; string-append: contract violation
; expected: string?
; given: 'bob
; argument position: 2nd
; [,bt for context]
> (before greet ~a) ; argument to greet is now passed to ~a before greet
gets it
> (greet 'bob)
"Hi, bob!"
; or, alternatively, instead of pre, let's do:
> (after greet list)
> (greet "bob")
'("Hi, bob!")
; or, how about full control?
> (around greet
(lambda (name)
(displayln "About to enter greet")
(inner (~a name))
(displayln "After greet"))
> (greet 'bob)
About to enter greet
"Hi, bob!"
After greet
Is there an equivalent in Racket?
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