The last thing: we made startsWithUpper less general in the process; it is undefined for empty strings. We need to verify that words never returns any empty strings. I did this using SmallCheck:

ghci> import Test.SmallCheck
ghci> smallCheck 10 $ \string -> all (not . null) (words string)

'Course, it turns out that SmallCheck never generates any spaces... ever. Some verifier that is.

By careful inspection of the definition of words, I can see that it never returns an empty string. I couldn't find a better way to convince myself of this (I like to avoid looking at definitions when possible).

Luke

Depth 0:
Completed 1 test(s) without failure.
Depth 1:
Completed 2 test(s) without failure.
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Completed 5 test(s) without failure.
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Completed 16 test(s) without failure.
Depth 4:
Completed 65 test(s) without failure.
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Completed 326 test(s) without failure.
Depth 6:
Completed 1957 test(s) without failure.
Depth 7:
Completed 13700 test(s) without failure.
Depth 8:
Completed 109601 test(s) without failure.
Depth 9:
Completed 986410 test(s) without failure.
Depth 10:
Completed 9864101 test(s) without failure.

So I am reasonably confident that words never gives me any empty strings.

Tada! Your solution is almost exactly the same as the one-liners! :-)

Luke