When an image is loaded, any alien objects which persisted from the previous session are marked as having expired. This is because the C pointers they contain are almost certainly no longer valid.
For this reason, the
ALIEN: word should not be used in source files, since loading the source file then saving the image will result in the literal becoming expired. Use
<alien> instead, and ensure the word calling
<alien> is not declared
flushable.
expired? ( c-ptr -- ? )