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clj-kondo 2026-07-15
borkdude 2026-07-15T20:45:46.471349Z
$ clj -M:clj-kondo/dev --lint - <<< '(defn foo [x] (if (string? x) (inc x) (subs x 1)))'
:1:36: warning: Expected: number, received: string.
linting took 39ms, errors: 0, warnings: 1 🆒 2
1
borkdude 2026-07-16T07:21:09.250489Z
the (if (string? x) ...) uncovers more of those redundant str calls ;)
seancorfield 2026-07-16T13:31:30.208459Z
Not in our code, it didn't. But one thing that impressed me mightily:
We have a utility fn, make-customer-id, that just calls format on its arguments. No type hints.
Lower down the code, there's a let with fk (make-customer-id site-id member-id) and below that we had (str fk)...
Kondo figured out that the result of make-customer-id would only be a string, so fk was a string, so the str call was redundant.
Impressive!
🎉 1
borkdude 2026-07-15T21:12:43.282499Z
Ah nice, found a real issue:
string-or-glob is a string here, the str call is redundantborkdude 2026-07-15T21:53:46.077059Z
@seancorfield just merged this, wonder if you will find anything (or in case of false positives, let me know of course!)
seancorfield 2026-07-15T22:17:56.286239Z
Thanks. In an hour or two, LSP should pick that up and produce a new nightly, then I'll restart VS Code to pick that up and test it.
seancorfield 2026-07-16T01:11:47.556799Z
Didn't find any Expected: type mismatch warnings in with the new version on our code at work.
seancorfield 2026-07-16T01:12:13.598569Z
We have a lot more Single argument to str already is a string than I realized 🙂
seancorfield 2026-07-16T01:19:25.504189Z
(we had a lot of code before we added clj-kondo!)