4 ms·

FWIW the first comment in that blog post shows that at the time of writing the post, the compiler could not detect that error.

• taeric 8y ago
  My suspicion is the author just didn't know how to use sbcl for this. I quickly tried this and did not receive any such message.
• aidenn0 8y ago
  That's fair. I would believe that error checking on lambdas has improved.