Re: [Haskell-cafe] How to deal with last item with concatMapAccumC in Conduit.

Dear all the runnable example code is as blow =================================================================== import Conduit import Text.Regex (matchRegex,mkRegex,Regex) loghead = mkRegex "^([0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2},[0-9]{3} )" -- "2015-01-25 00:04:18,840" logMerge::Regex->String->String->(String,[String]) logMerge logregex str accum = case matchRegex logregex str of Just _ -> (str,[(accum++"\n")]) Nothing -> case null accum of True -> (str,[]) False -> (accum ++ "<br>" ++ str,[]) runMerge::String->String->IO () runMerge infile outfile = runResourceT $ sourceFile infile $= linesUnboundedC $= concatMapAccumC (logMerge loghead ) "" $$ sinkFile outfile ================================================================ the example input file is --------- 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | | errorCode: toString() = null 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | codsexception.getErrorCode(): toString() { errorCode = "UNEXPECTED_PROBLEM" severity = "" } 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | | 2015-01-25 00:03:45,331 | DEBUG | WebContainer : 20 | | --------- the expected output is --------- 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | | errorCode: toString() = null 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | codsexception.getErrorCode(): toString() <br>{<br> errorCode =<br>"UNEXPECTED_PROBLEM"<br> severity = ""<br>} 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | | 2015-01-25 00:03:45,331 | DEBUG | WebContainer : 20 | | --------- the actual output is blow, missing the last line of log --------- 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | | errorCode: toString() = null 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | codsexception.getErrorCode(): toString() <br>{<br> errorCode =<br>"UNEXPECTED_PROBLEM"<br> severity = ""<br>} 2015-01-25 00:03:44,331 | DEBUG | WebContainer : 20 | | --------- Thanks

在 2017年7月19日，下午7:50，Michael Snoyman mailto:michael@snoyman.com> 写道：

I'm afraid I doon't follow what it meant by the stream here. Could you provide a complete, runnable example and indicate what the expected and actual output are?

On Mon, Jul 17, 2017 at 5:48 AM, jun zhang mailto:zhangjun.julian@gmail.com> wrote: Dear cafes

I use Conduit to parse a huge file. And I need merge lines by condition.

I find the concatMapAccumC can do that and I write a demo as blow(with conduit-combinators-1.0.6,lts-6.18). The problem is if the last item didn’t make condition true, the data only keep in the accum but missing in stream.

Any one can give me some advises?

Thanks

---------------------------- import Conduit

test'::Int->Int->(Int,[Int]) test' a s = case (a+s) > 5 of True -> (0,[a+s]) False -> (a+s,[])

testlog::IO [Int] testlog = runConduit $ (yieldMany [1,2,3,4,5,6,3]) $= (concatMapAccumC test' 0 ) $$ sinkList

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