[Haskell-cafe] Improvement suggestions
Hello everyone, I am quite new to monadic code so I would like to ask for improvement suggestions on the last line of the code below. I know I could do something like do strs - mapM ...; intercalate ... etc, but I would like to avoid the use of -. Thank you, José data XmlState = XmlState Int type XmlM a = State XmlState a loop :: Document - XmlM String someFn :: [Document] - XmlM String someFn docs = return concat `ap` (sequence $ intersperse (return \n) (map loop docs))--- improve this line -- José António Branquinho de Oliveira Lopes 58612 - MEIC-A Instituto Superior Técnico (IST), Universidade Técnica de Lisboa (UTL) jose.lo...@ist.utl.pt ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Improvement suggestions
On 15/08/12 17:01, José Lopes wrote: someFn docs = return concat `ap` (sequence $ intersperse (return \n) (map loop docs)) First of all, return x `ap` y = x `fmap` y or x $ y. fmap (or its infix synonym ($)) is the answer here, you could write: someFn docs = concat . intersperse \n $ mapM loop docs The function Data.List.intercalate is a compation of concat and intersperse, so you could write: someFn docs = intercalate \n $ mapM loop docs or, depending on your preference, someFn = fmap (intercalate \n) . mapM loop Twan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Improvement suggestions
Try: concat . intersperse \n $ (sequence $ map loop docs) On Wed, Aug 15, 2012 at 11:01 AM, José Lopes jose.lo...@ist.utl.pt wrote: Hello everyone, I am quite new to monadic code so I would like to ask for improvement suggestions on the last line of the code below. I know I could do something like do strs - mapM ...; intercalate ... etc, but I would like to avoid the use of -. Thank you, José data XmlState = XmlState Int type XmlM a = State XmlState a loop :: Document - XmlM String someFn :: [Document] - XmlM String someFn docs = return concat `ap` (sequence $ intersperse (return \n) (map loop docs))--- improve this line -- José António Branquinho de Oliveira Lopes 58612 - MEIC-A Instituto Superior Técnico (IST), Universidade Técnica de Lisboa (UTL) jose.lo...@ist.utl.pt __**_ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/**mailman/listinfo/haskell-cafehttp://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Improvement suggestions
Thank you. On 15-08-2012 23:09, Twan van Laarhoven wrote: On 15/08/12 17:01, José Lopes wrote: someFn docs = return concat `ap` (sequence $ intersperse (return \n) (map loop docs)) First of all, return x `ap` y = x `fmap` y or x $ y. fmap (or its infix synonym ($)) is the answer here, you could write: someFn docs = concat . intersperse \n $ mapM loop docs The function Data.List.intercalate is a compation of concat and intersperse, so you could write: someFn docs = intercalate \n $ mapM loop docs or, depending on your preference, someFn = fmap (intercalate \n) . mapM loop Twan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- José António Branquinho de Oliveira Lopes 58612 - MEIC-A Instituto Superior Técnico (IST), Universidade Técnica de Lisboa (UTL) jose.lo...@ist.utl.pt ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
