[Haskell-cafe] fmap use

Tom Ellis tom-lists-haskell-cafe-2017 at jaguarpaw.co.uk
Fri Dec 14 11:22:38 UTC 2018

On Fri, Dec 14, 2018 at 11:49:45AM +0100, Damien Mattei wrote:
> another question with Haskell, again with my database but that is again
> related to Monads:

Damien, it's very hard to read your posts because they consist of snippets
of code interspersed with commentary.  You'll probably get much better
responses if you post single, very small, well-formatted examples of sample

Anyway, the ultimate answer to your query is "use do-notation".  Your
getBS_WDS would be clearer written something like:

getBD_WDS :: Connection -> String -> IO Float
getBD_WDS conn name = do
    let qry_head = "select DNUM from WDS where DISC = ?" :: Query

    bd_rows <- query conn qry_head (Only name)

    let noBDtxt :: Text
        noBDtxt = fromOnly (Prelude.head bd_rows)

        noBDstr :: String
        noBDstr = Text.unpack noBDtxt

        noBDfp :: Float
        noBDfp = read noBDstr

    return noBDfp


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