#!optional arguments are not "evaluated in an environment in which all previous parameters have been bound."

[Alan Post]

Chicken Scheme uses DSSSL style lambda lists, as an extension to standard scheme:

​http://wiki.call-cc.org/man/4/Extensions%20to%20the%20standard

Optional parameters are permitted to have an initializer, and the documentation states:

"The corresponding <initializer> is evaluated in an environment in which all previous parameters have been bound."

I would expect the following to work (note that a1 is being bound to the value of a0):

(define (foo #!optional a0 (a1 a0))

(list a0 a1))

(foo) => (#f #f)
(foo 0) => (0 0)

However, I instead get the following error:

Note: the following toplevel variables are referenced but unbound:

a0 (in def-a123)

I've attached a test case for #!optional parameters testing additional cases.

I'm running chicken scheme from git, commit cd19d7e077f0a6b53c3c804c972ec3738683e9ab.

My platform is OpenBSD 4.8-snapshot.

[Alan Post]

test case designed to be placed in chicken-core/tests/

[sjamaan]

Likely fixed by changing let-optionals to let-optionals* in expand.scm:374

[felix winkelmann]

Using let-optionals* is not only correct, it also generates faster and smaller code. Thanks a lot, Alan! I added the testcase (and fixed a few problems with it).

[felix winkelmann]

Milestone 4.7.0 deleted

[felix winkelmann]

Milestone 4.8.0 deleted