Could be that (the libreadline on macOS). Here’s the character: :grinning:

It happens with other Unicode characters as well, for example when trying to copy the examples with a Lambda character from the Racket docs

And it happens in the Racket REPL as well, so it must be something with the readline library I guess

[~]─> racket
Welcome to Racket v7.1.
> (\U+FFCE\U+FFBB (x) (* 2 x))
; x: undefined;
;  cannot reference an identifier before its definition
;   in module: top-level
; [,bt for context]
> (lambda (x) (* 2 x))
#<procedure>

the \U+FFCE\U+FFBB is what I get after copy-pasting the lambda character from https://docs.racket-lang.org/reference/lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29

Ha, Slack is so helpful that when I copy the character I get the text «:grinning:» instead of unicode… But it sounds like it is libreadline on MacOS. At some point Rash will definitely move away from using readline, but I can’t give a timeline for that. Definitely not in 2018.

(of course it interpreted the text back into am emoji… colon grinning colon)

You can also run rash-repl with readline disabled, though then you have no editing…

@willghatch thanks for looking into this. It’s no big deal :slightly_smiling_face: I’m still in the process of learning Racket, and I will start poking more into the code as I learn. Hopefully at some point I can start contributing some things.