Comp150CPA Message 0023.txt from Alva L. Couch(couch)
OOPS! I made an error on this page:
Q: How can I get the bud simulator to work? It doesn't seem to...
A: I played with it a bit just now and made sure that I installed
FLASH: I made an error in the following example:
rebl> table :friends, [:f1,:f2]=>[:f3]
rebl> friends <= [['alva', 'george', 1]]
rebl> friends <= [['alva', 'fred', 1]]
rebl> stdio <~ friends
exception: Exception during Bud evaluation.
Exception: #<Bud::KeyConstraintError: Key conflict inserting ["alva", ["fred", 1]] into "stdio": existing tuple ["alva", ["george", 1]], key_cols = ["alva"]>.
Rule: stdio < (friends.~)
The reason that this didn't work is that I should have written
stdio <~ friends.inspected
stdio <~ friends
Note: I took my lecture examples from the "bud cheat sheet" on the website.
I was expecting you to do the exam *without* invoking the simulator.
It is possible to do just from the "meanings" of the operators.
Last changed Tue May 10 17:40:04 2011