On 24-07-2022 03:21, Zelphir Kaltstahl wrote:

> ~~~~
> (define-syntax require
>    (identifier-syntax
>     (syntax-error "'require' can only be used as part of a contract construct")))
> ~~~~
>
> Can you explain how it works?
>
If you meant: how can identifier-syntax + syntax-error be used? -- I 
don't have more information than the explanations in the manual on 
identifier-syntax and syntax-error.

If you meant: how does it work?  I don't know how Guile's macro system 
is implemented, you'll have to look at the source code of (ice-9 
psyntax), maybe read the paper it cites.

If you meant: how to use it? All you have to do is replace your (define 
require ...) by the (define-syntax require ...)

Greetings,
Maxime