#clojure – 2008-05-20

2008-05-20

11:42	ozzilee	Does clojure have a test suite?
11:51	rhickey	no
11:55	ozzilee	Ok. I'm playing around with a test library and some clojure tests, just wanted to make sure I wasn't completely wasting my time.
12:31	ozzilee	Oddity: (peek [1 2 3 4]) is 4, (peek (seq [1 2 3 4])) is an error.
12:32	ozzilee	What's expected behavior there?
12:33	rhickey	peek is a function of lists, vectors and queues, not seqs
12:34	ozzilee	seqs are the most general of the four, correct?
12:35	rhickey	not sure what you mean by general
12:36	ozzilee	Superclass maybe? Are lists, vectors and queues all seqs?
12:37	rhickey	no - seq is something that can be obtained on a collection - a sequential view. Some collections are their own seqs (lists) but others are not (vectors/maps)
12:38	ozzilee	Something like an iterator then?
12:38	rhickey	not quite - iterators ar estateful and single-pass
12:39	rhickey	http://n01se.net/paste/HTx
12:44	jteo	iterators. ugh.
12:45	ozzilee	So should (peek (seq '(1 2 3 4))) work? Ideally, I mean. It works currently.
12:51	rhickey	It works, but implies no more about whether the result of seq should support peek than (peek (identity '(1 2 3 4))) implies about the result of identity
12:54	ozzilee	Ok. I'll write tests for the behavior as-is.
12:54	rhickey	what are you testing in that case?
12:58	ozzilee	(= (peek (seq '(1 2 3 4)) 1))
12:59	ozzilee	rather, (test/= "peek (seq list)" (peek (seq '(1 2 3 4))) 1)
12:59	ozzilee	for vectors: (test/exception "peek (seq vector)" (peek (seq [1 2 3 4])))
13:02	rhickey	but what is the logical test? tests should have a basis, i.e. that lists/vectors support peek. But in this case you are passing the return value of seq, which is not guaranteed to support peek. Such a test has no logical basis, it only serves to freeze current behavior, which is subject to change, i.e. if lists are no longer their own seqs (it's not guaranteed that they will be), which has nothing to do with peek
13:10	ozzilee	I see your point. I'll consider the behavior unspecified then.
13:11	ozzilee	Can I consider it specified that (peek {1 2}) is an exception?
13:14	ozzilee	I suppose not.
13:27	ozzilee	(pop []) is documented as throwing an exception (on the website), it actually throws an Error. Which is correct?
13:28	ozzilee	Or should I just take note and post to the list and stop bugging you? :-)
14:08	rhickey	I think the focus. being a dynamic language, should be to test that things that ought to work do. Things that don't work might be made to work as an enhancement at some point
14:09	ozzilee	I agree, I'm not going to test (peek <map>).
14:41	ozzilee	DId you get my message about (pop []) ?
14:56	rhickey	(pop []) now throws IllegalStateException, all other usage of IllegalAccessError have been removed as well
14:57	ozzilee	Good deal.
15:37	ozzilee	(keys {}) returns nil. I assume that's proper, seeing as there is no empty Sequence. Correct?
15:39	rhickey	all functions that return seqs either return a seq with items or no seq - nil
15:41	ozzilee	Ok, just making certain. Thanks.