CODEWITHSUNDEEP
scheme
user2608895
user2608895

Reputation: 11

Scheme: Why isn't my defined procedure being recognized?

(define rearrange 
  (λ ignore
    (define (proc1 x y) (+ x y))
    (foldr (λ (x y) (if (list? x) (append (rearrange x y) y) 
                        (if (procedure? x) 
                            (append y (list x)) (cons x y)))) empty '(a proc1 b))))

why isn't x being recognized as a procedure even though I defined it as such right before the call to foldr?

Upvotes: 0

Views: 57

Answers (1)

Alexis King
Alexis King

Reputation: 43842

Nope. In that list, and is not a procedure. It is a symbol.

This is due to how quoting works. The expression '(a b c) is effectively the same as (list 'a 'b 'c), so and is literally evaluated as the symbol, 'and.

Either explicitly use the list function to make your list, or use quasiquoting. Either of these expressions should produce what you want:

(list 'a and 'b)
`(a ,and b)

Upvotes: 1

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