On 03/07/2012 12:31 PM, Gabriel Scherer wrote: > You can inject the definition you want in the following way: > > module Meths = struct > include Meths > module Show_t = ... > end > > type value_kind = ... > deriving (Show) > > This works because deriving, being a Camlp4 extension, does not refer > to "the" module Meths, but any module Meths that is in scope at the > place of expansion. This could be seen as a defect of hygiene (indeed > that makes camlp4 macro non-hygienic according to the Scheme notion of > hygiene) but is also a feature, rather than a bug, of the syntactic > macro system; because as a macro-writer you can give flexibility to > the user by specifying the free variables you rely on.
I have never used "include" construct myself but I always wanted it. Its cool that we have it :-) The above problem can indeed be solved, i.e. pretty-printer can be generated in this way. The tricky part is to figure out how to define the "Show_t" module definition, which is non-obvious. -- Caml-list mailing list. Subscription management and archives: https://sympa-roc.inria.fr/wws/info/caml-list Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
