On Tue, Oct 28, 2014 at 10:30 AM, Konrad Hinsen <konrad.hin...@fastmail.net> wrote: > Konrad Hinsen writes: > > > I have added lots of comments to my minimalistic typed language > > implementation, in the hope that future language definers will > > be able to pick up from there: > > > > http://github.com/khinsen/racket-typed-lang > > There is still one problem, although I am not convinced that it can be > fixed in the language definition. > > The following code fails because 'foo' is considered an unbound identifier: > > --- test1.rkt ------------------------------------ > #lang racket/base > > (module example a-typed-lang > (displayln (foo 42))) > > (require 'example) > -------------------------------------------------- > > Strangely enough, as soon as my submodule has two forms it works, e.g. > > --- test2.rkt ------------------------------------ > #lang racket/base > > (module example a-typed-lang > (displayln (foo 42)) > (displayln (foo 42))) > > (require 'example) > -------------------------------------------------- > > The documentation for "module" at > http://docs.racket-lang.org/reference/module.html?q=module#%28form._%28%28quote._~23~25kernel%29._module%29%29 > > suggests that single-form modules are handled differently than multi-form > modules, which might well explain this phenomenon. However, it doesn't provide > any clue to a solution. Apparently, my single form is > > "partially expanded in a module-begin context. If the expansion > leads to #%plain-module-begin, then the body of the > #%plain-module-begin is the body of the module." > > Furthermore: > > "Finally, if multiple forms are provided, they are wrapped with > #%module-begin, as in the case where a single form does not expand > to #%plain-module-begin." > > This suggests that if I want my single-form module to be handled exactly > like a multi-form module, my single form must expand to something else > than #%plain-module-begin. Fine. But who or what decides what my single > form becomes when it is "partially expanded in a module-begin context" ?
This always happens in a single-form module. The macro system partially-expands the macro to see if it turns into a version of #%module-begin. Sam ____________________ Racket Users list: http://lists.racket-lang.org/users
