EVAL limitations

[kchanqvq]

(let ((name (gensym)))
  (eval `(defvar ,name "FOO"))
  (symbol-value name))

errors, but

(let ((name 'foo))
  (eval `(defvar ,name "FOO"))
  (symbol-value name))

works.

The reason is dump-symbol creates a different symbol, if and only if the symbol is uninterned.

(eval some-atom) should also works for any atom, but in fact does not work for objects which literal/dump-* doesn't know how to dump.

I'm not sure the right way to fix this. I think maybe dump-* logic should have two mode -- in compilation mode it should dump everything and errors if it doesn't know how to dump; in eval mode it prefers just keeping a reference to the original object. But I'm not sure about the details yet.

[davazp]

I wonder if this was another bootstrap specific logic, and the logic could be in bootstrap vs non-bootstrap mode instead?

[kchanqvq]

I wonder if this was another bootstrap specific logic, and the logic could be in bootstrap vs non-bootstrap mode instead?

I don't think this is (directly) related to bootstrap. The root cause is that we have a compiler only implementation, but eval suppose to support more code than what can be compiled into file (e.g. those that contain arbitrary literal objects). I'll take a look at how SBCL handles this!

[kchanqvq]

SBCL does treat constant differently for in-process compile and file compile. I think it stores a constant vector for each component, which either store reference to the constant directly (for in-process), or filled by MAKE-LOAD-FORM (for file compile).