Re: [Haskell-cafe] parsec or attoparsec for 40-50MB text files ?

offtopic, but since we are talking about Parsec/Attoparsec, is there a way to have try by default in Parsec as well? On Mon, Jun 8, 2015 at 9:23 AM Chris Wong wrote:

Hi Brian,

Parsec and Attoparsec have very similar interfaces (afaik the only difference is that Attoparsec backtracks by default, so the "try" combinator is a no-op) so there's no harm in trying both.

Alternatively: if the data format is simple enough, you can write the parser by hand. The Data.Text.Read module may help if you pursue this option. [1]

Chris

[1]: https://hackage.haskell.org/package/text-1.2.1.1/docs/Data-Text-Read.html

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Hi,

My file is pretty straightforward text file with a small amount of somewhat annoying state:

comments* config line comments* data line*

if there is no config line it's an error. the data lines can have a variable number of values and it matters how many values there are (hey- it's not my file format !). the data lines can also have a comment at the end.

My initial thought was to go with parsec but the data files could be as large as 40-50MB and upon further reading it really seemed like attoparsec would be better. Error handling wouldn't be too sophisticated. if a data

On Mon, Jun 8, 2015 at 11:04 AM, wrote: line has something other than 1 or more floating point values and the optional comment, failing out with "error line X" is fine.

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parse time is somewhat critical only because i'll have multiple files to

parse, so while 5-10 seconds is ok for one file, i have to multiply that by 5-10.

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I've seen several comments talking about the fact that parsec can be

slow, but so far unable to find anything the quantifies "slow".

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Any opinions on which would be better for my application (although i

think i've just talked myself into using attoparsec) ?

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In particular- am i going to get at least reasonable "error on line X"

error handling using attoparsec ?

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Thanks,

Brian

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