Xtext

1. Xtext Typesystem Framework http://code.google.com/a/eclipselabs.org/p/xtext-typesystem/ Markus Voelter independent/itemis

2. Typesystem (from Wikipedia) In computer science, a type system may be defined as a tractable syntactic framework for classifying phrases according to the kinds of values they compute. A type system associates types with each computed value. By examining the flow of these values, a type system attempts to prove that no type errors can occur. The type system in question determines what constitutes a type error, but a type system generally seeks to guarantee that operations expecting a certain kind of value are not used with values for which that operation makes no sense.

3. Typesystem (from Wikipedia) In computer science, a type system may be defined as a tractable syntactic framework for classifying phrases according to the kinds of values they compute. A type system associates types with each computed value. By examining the flow of these values, a type system attempts to prove that no type errors can occur. The type system in question determines what constitutes a type error, but a type system generally seeks to guarantee that operations expecting a certain kind of value are not used with values for which that operation makes no sense.

4. Typesystem (from Wikipedia) In computer science, a type system may be defined as a tractable syntactic framework for classifying phrases according to the kinds of values they compute. A type system associates types with each computed value. By examining the flow of these values, a type system attempts to prove that no type errors can occur. The type system in question determines what constitutes a type error, but a type system generally seeks to guarantee that operations expecting a certain kind of value are not used with values for which that operation makes no sense.

5. Typesystem (from Wikipedia) In computer science, a type system may be defined as a tractable syntactic framework for classifying phrases according to the kinds of values they compute. A type system associates types with each computed value. By examining the flow of these values, a type system attempts to prove that no type errors can occur. The type system in question determines what constitutes a type error, but a type system generally seeks to guarantee that operations expecting a certain kind of value are not used with values for which that operation makes no sense.

7. x: Var y: Calc type type expr IntType IntType Plus left right IntConst Multi left right IntConst Sqrt expr VarRef

8. declarefixedtypes x: Var y: Calc type type expr IntType IntType Plus int int left right IntConst Multi int left right double IntConst Sqrt int expr VarRef

9. declarefixedtypes derivetypes x: Var y: Calc int type type expr IntType IntType Plus int int left right IntConst Multi int left right double IntConst Sqrt int expr VarRef int

10. declarefixedtypes derivetypes calculatecommon x: Var y: Calc (type hierarchies) int type type expr double IntType IntType Plus int int left right IntConst Multi int double left right double IntConst Sqrt int expr VarRef int

11. declarefixedtypes derivetypes calculatecommon x: Var y: Calc (type hierarchies) int check types type type expr double IntType IntType Plus int int left right ! ! ! ! ! ! ! IntConst Multi int double left right double IntConst Sqrt int expr VarRef int

12. declarefixedtypes derivetypes calculatecommon (type hierarchies) check types Xtext Typesystem Framework Demo

13. declarefixedtypes derivetypes calculatecommon (type hierarchies) check types Xtext Typesystem Framework Editor:popuptoshow type information use type information in scopes Debug:tracetohelp understand how type was calculated Testing:internal Java DSL fortestingthetypesystemrules Docs: 22-page tutorial

14. declarefixedtypes derivetypes calculatecommon (type hierarchies) check types Xtext Xtext Typesystem Framework Try it: http://code.google.com/a/eclipselabs.org/p/xtext-typesystem/