How should I convert a single-character string to a char? What have been doing is string->list followed by car. I can’t find a function that does this directly.

(string-ref "a" 0)

Shame on me! Thanks!

Does racket not support recursive structs? As in, the following does not seem to work > (struct recursive-point2d (x y p)) > (letrec ([p (recursive-point2d 0 0 p)]) p) ; p: undefined; ; cannot use before initialization ; [,bt for context]

Use shared. https://docs.racket-lang.org/reference/shared.html?q=shared#%28form._%28%28lib._racket%2Fshared..rkt%29._shared%29%29

Or make your struct mutable, and set the p after construction

What’s reason behind letrec not handling this and having a separate shared form?

It would make letrec substantially more complex, and also it allows data structures that are not constructible otherwise

such as your recursive point

> It would make letrec substantially more complex Is there something that letrec can do that shared cannot? Also, is shared a racket-specific form or a scheme form? I looked up http://schemers.org\|schemers.org, couldn’t find anything.

shared is Racket-specific

also, letrec is built-in and (mostly) can’t be implemented yourself

for example, to create a recursive procedure