Theory Value

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theory Value
imports Type

(*  Title:      HOL/Bali/Value.thy
Author: David von Oheimb
*)

header {* Java values *}



theory Value imports Type begin

typedecl loc --{* locations, i.e. abstract references on objects *}

datatype val
= Unit --{* dummy result value of void methods *}
| Bool bool --{* Boolean value *}
| Intg int --{* integer value *}
| Null --{* null reference *}
| Addr loc --{* addresses, i.e. locations of objects *}



consts the_Bool :: "val => bool"
primrec "the_Bool (Bool b) = b"
consts the_Intg :: "val => int"
primrec "the_Intg (Intg i) = i"
consts the_Addr :: "val => loc"
primrec "the_Addr (Addr a) = a"

types dyn_ty = "loc => ty option"
consts
typeof :: "dyn_ty => val => ty option"
defpval :: "prim_ty => val" --{* default value for primitive types *}
default_val :: " ty => val" --{* default value for all types *}


primrec "typeof dt Unit = Some (PrimT Void)"
"typeof dt (Bool b) = Some (PrimT Boolean)"
"typeof dt (Intg i) = Some (PrimT Integer)"
"typeof dt Null = Some NT"
"typeof dt (Addr a) = dt a"


primrec "defpval Void = Unit"
"defpval Boolean = Bool False"
"defpval Integer = Intg 0"

primrec "default_val (PrimT pt) = defpval pt"
"default_val (RefT r ) = Null"


end