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Date: | 1997-06-10 (07:19) |
From: | Wolfgang Lux <lux@h...> |
Subject: | Re: Unbound row variable in #basic_bloc |
> Bonjour, > > J'ai pas trouve l'explication de ce message d'erreur dans la documention > d'objective caml 1.05. Cela survient lorsque je fait : > > type node_t=#basic_bloc > > Si quelqu'un pouvait me donner des indications ? Yes (sorry, it seems as if I should learn french real soon now, but until then you live with an english answer only :-). Let us assume you has defined basic_bloc as follows: class basic_bloc () method do_nothing = () end then the types basic_bloc and #basic_bloc would be have been defined as follows: basic_bloc = < do_nothing : unit > #basic_bloc = < do_nothing : unit; .. > Note the ellipsis ".." in the second. This is an anonymous row variable. (Row variables are used to describe and type extensible records, but in the implementation of Ocaml they are not available to user. Actually the only row variable you will ever encouter in Ocaml explicitly is the ellipsis ".."). Row variables, just like type variables must be bound somewhere, but if you try to define type node_t = #basic_bloc then ".." is unbound. Regards Wolfgang