src/HOL/NanoJava/TypeRel.thy

 
 theory TypeRel
 imports Decl
 begin
 
-text{* Direct subclass relation *}
+text\<open>Direct subclass relation\<close>
 
 definition subcls1 :: "(cname \<times> cname) set"
 where
   "subcls1 \<equiv> {(C,D). C\<noteq>Object \<and> (\<exists>c. class C = Some c \<and> super c=D)}"
 

   where "C \<preceq>C D == (C,D) \<in> subcls1^*"
 
 
 subsection "Declarations and properties not used in the meta theory"
 
-text{* Widening, viz. method invocation conversion *}
+text\<open>Widening, viz. method invocation conversion\<close>
 inductive
   widen :: "ty => ty => bool"  ("_ \<preceq> _" [71,71] 70)
 where
   refl [intro!, simp]: "T \<preceq> T"
 | subcls: "C\<preceq>C D \<Longrightarrow> Class C \<preceq> Class D"

 apply (drule wf_subcls1)
 apply (subst def_wfrec[OF class_rec_def], auto)
 apply (subst cut_apply, auto intro: subcls1I)
 done
 
---{* Methods of a class, with inheritance and hiding *}
+\<comment>\<open>Methods of a class, with inheritance and hiding\<close>
 definition "method" :: "cname => (mname \<rightharpoonup> methd)" where
   "method C \<equiv> class_rec C methods"
 
 lemma method_rec: "\<lbrakk>class C = Some m; ws_prog\<rbrakk> \<Longrightarrow>
 method C = (if C=Object then empty else method (super m)) ++ map_of (methods m)"

 apply (erule (1) class_rec [THEN trans])
 apply simp
 done
 
 
---{* Fields of a class, with inheritance and hiding *}
+\<comment>\<open>Fields of a class, with inheritance and hiding\<close>
 definition field  :: "cname => (fname \<rightharpoonup> ty)" where
   "field C \<equiv> class_rec C flds"
 
 lemma flds_rec: "\<lbrakk>class C = Some m; ws_prog\<rbrakk> \<Longrightarrow>
 field C = (if C=Object then empty else field (super m)) ++ map_of (flds m)"