At Wed, 25 Aug 2010 19:52:17 -0400, Danny Yoo wrote: > I see that the error messages regarding toplevel variables are > slightly different, depending on context. e.g. set! can produce > either the error message > > set!: unbound identifier in module in: x
That's a syntax error. > or the message: > > set!: cannot set undefined variable: x That's a run-time error. > I'm trying to understand what's happening. How does set! know in what > context (definitions or interactions) it is being used? The `module', `#%top', and `set!' forms of `racket/base' conspire. The `#%top' and `set!' forms know when they are being expanded within a `module', and they raise a syntax error in that case. > What in the > documentation should I be looking at to better understand this? Maybe `#%top' or `set!', but the documentation could be clearer. For example, whenever the documentation specifies an exception (as it does for `set!' on an undefined top-level variable), it means that the exception is at run time, but that probably isn't clear enough. _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
