Hi Jasmin, thanks for the quick reply. Your suggestion works fine!
cheers chris On 12/03/2014 03:46 PM, Jasmin Christian Blanchette wrote:
Hi Chris,is there a reliable way to check - given the name of a type constructor - how many dead type parameters it has? I tried (case BNF_FP_Def_Sugar.fp_sugar_of lthy tname of SOME sugar => if BNF_Def.dead_of_bnf (#fp_bnf sugar) > 0 then error "..." ... However having something like datatype foo = Foo | Bar I noticed that print_bnfs does not list type "foo",It doesn't because it's a nullary BNF and all types are trivially nullary BNFs, so there's no point in storing this pointless information in our databases. Instead, we store only a single such type, namely 'a, where 'a is dead. This BNF is called DEADID -- it's listed when you execute "print_bnfs", and you can grep for it in "src/HOL/*.thy" to find out where it is registered. So when you look up "foo", you get, somewhat confusingly, the BNF entry for 'a. A more reliable way to count the number of deads is to use the equation: num_dead_vars = num_type_vars - num_live_vars "BNF_Def.live_of_bnf" and "Sign.arity_number" are your friends. I hope this solves your problem. Don't hesitate to let us know if you run into issues again. Those interfaces were never very polished, nor documented (although I might come to add a section to "isabelle doc datatypes" about the ML functions -- there is an embryonic, commented out "Using the Standard ML Interface" section already). Cheers, Jasmin
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