On Wed, Feb 22, 2017 at 09:02:22PM +0900, S. H. Aegis wrote:
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.
Then this: makeRxDxList :: Text -> [[Text]] makeRxDxList rowRxDx = fmap f (lines rowRxDx) -- you imported Prelude hiding map, so we will use fmap where f :: Text -> [Text] f x = splitOn (pack ",") x should do (at least it typechecks). GHC errors may not have the prettiest formatting ever, but they are very useful, the most important bits being line & column of the offending expression plus the "expected this but got that" part; get acquainted with them!