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I followed the directions on the Rosette website to download rosette (https://docs.racket-lang.org/rosette-guide/ch_getting-started.html). It seems that I can run this program and get an output error free.

    #lang rosette/safe

; Compute the absolute value of `x`.
(define (absv x)
  (if (< x 0) (- x) x))

; Define a symbolic variable called y of type integer.
(define-symbolic y integer?)

; Solve a constraint saying |y| = 5.
(solve
  (assert (= (absv y) 5)))

However, when I try running this or any similar program using more than the basic racket keywords I get unclear (to me) errors.

#lang rosette

(struct plus (left right) #:transparent)
(struct mul (left right) #:transparent)
(struct square (arg) #:transparent)

(define prog (plus (square 7) 3))

(define (interpret p)
  (destruct p
    [(plus a b)  (+ (interpret a) (interpret b))]
    [(mul a b)   (* (interpret a) (interpret b))]
    [(square a)  (expt (interpret a) 2)]
    [_ p]))

(interpret prog)

This gives me an error destruct: unbound identifier in: destruct. What is going on? This code is not my own and is copy pasted from a tutorial so it should work I think. I have also tried example code copy pasted from the Rosette website and that gives similar errors. I've followed all the installation instructions and updated the environment path etc. Any help?

MathStudent
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1 Answers1

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destruct is not provided by #lang rosette by default. You need to require it by writing:

 (require rosette/lib/destruct)

after #lang rosette

Where did you find this code, by the way?

Sorawee Porncharoenwase
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  • Thank you! I found the code from this article https://www.cs.utexas.edu/~bornholt/post/building-synthesizer.html – MathStudent Oct 22 '21 at 14:10
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    Ah, that post doesn't fully show all code, but the gist that is linked to from the post does have full code: https://gist.github.com/jamesbornholt/b51339fb8b348b53bfe8a5c66af66efe – Sorawee Porncharoenwase Oct 22 '21 at 14:38