Try replacing `safe-function-set` with: (define safe-function-set (list $+ $- $* $/))
Sam On Fri, Jan 3, 2014 at 5:28 PM, Rian Shams <rian.sh...@gmail.com> wrote: > Hello, > > I am working with functions that I have defined to only take 1 or 2 operands > (called safe-functions) for the implementation of a genetic program. > > (define ($+ augend addend) ;operation is addition > (+ augend addend)) ; the result is the sum > (define ($- minuend subtrahend) ;operation is subtraction > (- minuend subtrahend)) ;result is difference > (define ($* multiplicand multiplier) ;operation is multiplication > (* multiplicand multiplier)) ;result is product > (define ($/ dividend divisor) ;operation is division > (/ dividend divisor)) ;result is quotient > > (define (infinity? x) (or (eq? x +Inf.0) (eq? x -Inf.0))) > (define ($sin x) (if (infinity? x) (* (sgn x) +Inf.0) (sin x))) > (define ($cos x) (if (infinity? x) (* (sgn x) +Inf.0) (cos x))) > > (define safe-function-set > '($+ > $- > $* > $/ > ;$sin > ;$cos)) > > (define (select-random-safe-function) > (list-ref safe-function-set (random (length safe-function-set)))) > > I would like to use procedure-arity (or a similar function) to determine the > arity of a randomly selected safe function but I get this error: > >>(procedure-arity (select-random-safe-function)) > error: procedure-arity: contract violation > expected: procedure? > given: '$+ > > I think the problem is that the safe-functions are passed to procedure-arity > quoted. Is there a way I can unquote the functions, or adjust > procedure-arity to make (procedure-arity (select-random-safe-function)) > work? > > Thanks, > -- > Rian Shams > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
