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Iustin Pop authored
While removing split instances check from hcheck, I saw a wrong use of 'length': this should only be used when one needs the actual length of the list, and not when one wants to check whether the list is empty or not (in that case, 'null' should be used). To prevent this in the future, let's add a hlint hint for it, and fix the warning it generates in hbal. Signed-off-by:
Iustin Pop <iustin@google.com> Reviewed-by:
Agata Murawska <agatamurawska@google.com>
0c76f280
lint-hints.hs 432 B
-- The following two hints warn to simplify e.g. "map (\v -> (v,
-- True)) lst" to "zip lst (repeat True)", which is more abstract
warn = map (\v -> (v, x)) y ==> zip y (repeat x)
where _ = notIn v x
warn = map (\v -> (x, v)) ==> zip (repeat x)
where _ = notIn v x
-- The following warn on use of length instead of null
warn = length x > 0 ==> not (null x)
warn = length x /= 0 ==> not (null x)
warn = length x == 0 ==> null x