Core's approach to this is to use options. (Technically, we use a type called Or_error.t, which has a useful error message in the error-variant, but it's the same idea.)
On Thu, May 10, 2012 at 2:44 PM, Goswin von Brederlow <goswin-...@web.de> wrote: > Yitzhak Mandelbaum <yitzh...@cs.princeton.edu> writes: > >> Hi, >> >> Is there any "common wisdom" regarding the inclusion of optional functions >> in a module signature? The two most obvious approaches involve 1) a pair of >> boolean flag and a function, where the function raises an exception if >> unimplemented OR 2) using the option type. I see pros/cons to each approach, >> but am curious if there's any (unofficial) standard approach. >> >> Yitzhak >> ----------------------------- >> Yitzhak Mandelbaum > > The extunix module has a trifold solution for this: > > * First there is the ExtUnix.All module that has all functions in > it. Functions that are not available raise Not_available with function > name as an argument. > > * Second there is ExtUnix.All.have : string -> bool option > > (** [have name] > @return indication whether function [name] is available > - [Some true] if available > - [Some false] if not available > - [None] if not known > > e.g. [have "eventfd"] > *) > > * Third there is ExtUnix.Specific containing only functions available on > this platform. > > MfG > Goswin > > -- > 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 > -- 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
