Thank you so much.
--makeRxDxList :: Functor f => f Text -> f [Text]
Above signature comes from ghci using command :t
My intention is
makeRxDxList :: Text -> [[Text]]
but, I got error, and try several times and below codes pass a complier.
makeRxDxList rowRxDx = fmap (\x -> splitOn (pack ",") x) rowRxDx -- This
code pass a compile.
and then, I run ghci, type :t, and got below signature.
makeRxDxList :: Functor f => f Text -> f [Text]
Your kind answer says, I cannot help using fmap. right? ^^;
Thanks again.
2017-02-22 18:35 GMT+09:00 Francesco Ariis
On Wed, Feb 22, 2017 at 05:33:01PM +0900, S. H. Aegis wrote:
Hello. I'm new to Haskell and this is the first time I use Data.Text module. And using stack on OSX 10.12.3 I'm try several times, but fail. and I don't understand what error message says. How can I fix this? Thank you a lot.
Hello SH, Text.map has signature `(Char -> Char) -> Text -> Text`, so I expect you to need fmap too if the return value of makeRxDxList has type f [Text]
makeRxDxList rowRxDx = fmap _ rowRxDx -- or base map
_ is a hole and if the compiler will tell you which function needs to go there, in this case one with signature `Text -> [Text]`.
Does that help? If not, provide makeRxDxList signature and a brief description so it's easier to diagnose the problem -F _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
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