Arc Forum | Is the sort function broken in 3.2?

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2 points by daviddh 1358 days ago | 2 comments

I was working through the Arc tutorial and ran into an error when using the sort function:

(sort (fn (x y) (< (len x) (len y))) '("orange" "pea" "apricot" "apple"))

Error: "set-car!: expected argument of type <pair>; given: 560365568"

1 point by akkartik 1358 days ago | link

I can reproduce it. And it doesn't seem to depend on the comparison function:

 arc> (sort < '("orange" "pea" "apricot" "apple"))
 Error: "set-car!: expected argument of type <pair>; given: 577273856"

What version of Racket are you using? I'm running 8.2, and I see some weirdness:

 arc> (let x '("orange" "pea" "apricot" "apple") (= (car x) 1))
 1
 arc> (let x '("orange" "pea" "apricot" "apple") (= (car x) 1) x)
 Error: "invalid memory reference. Some debugging context lost"

The "bleeding edge" community repo at https://github.com/arclanguage/anarki doesn't seem impacted.

Edit 14 minutes later: looks like 7.7 shows identical errors.

Edit 45 minutes later: all this works fine with Racket 6.0. That version was already dealing with immutable lists by default (https://download.racket-lang.org/releases/6.0/doc/compatibil...), so I'm inclined to consider this a regression in Racket.

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2 points by daviddh 1358 days ago | link

Thanks for investigating this issue. I'm using Racket 8.2. I'll check out the community version you referenced.

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