Note: information on this page refers to Ceylon 1.1, not to the current release.

Type mapping annotations

Ceylon uses Java annotations in compiled .class files to store information about Ceylon types. For example, consider the Ceylon method:

Object? m() {
    // ...
}

In Ceylon, the return type (after syntactic desugaring) is Object|Null, and the compiler needs to know this when typechecking code which depends on m().

Currently, these annotations do not form a stable API which can be used by Java application developers wishing to customize how their Java types are treated by Ceylon. For this reason they are not documented here. If you're desperate to customise something you can look at the annotations in com.redhat.ceylon.compiler.java.metadata in ceylon.language.