Re: parse error on input when print specified lines of a file

Path	csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.haskell
Subject	Re: parse error on input when print specified lines of a file
Date	Wed, 24 Aug 2016 10:07:56 +0100
Organization	A noiseless patient Spider
Lines	30
Message-ID	<87wpj6pmab.fsf@bsb.me.uk> (permalink)
References	<cc369812-eba8-4c76-86e0-3f06e1e91d59@googlegroups.com> <87d1kzst3t.fsf@bsb.me.uk> <ee88453c-d7f6-412e-8959-bd938587d8f8@googlegroups.com>
Mime-Version	1.0
Content-Type	text/plain
Injection-Info	mx02.eternal-september.org; posting-host="017616aa25f81ec581c44d76d61ba2f3"; logging-data="4901"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/E9jI1mE8F07K8DuONV9n0X9Bb1Iq9Ze0="
Cancel-Lock	sha1:PaIpgtktLMBM9PhXNsM7abagHlg= sha1:A0tYq5Hu0ZCw7F0ijZpGRDUo154=
X-BSB-Auth	1.18de7174d82db2895a70.20160824100756BST.87wpj6pmab.fsf@bsb.me.uk
Xref	csiph.com comp.lang.haskell:459

Show key headers only | View raw

meInvent bbird <jobmattcon@gmail.com> writes:
>
> On Tuesday, August 23, 2016 at 6:00:07 PM UTC+8, Ben Bacarisse wrote:
>> meInvent bbird <jobmattcon@gmail.com> writes:
>> 
>> > parse error on input `\'
>> >
>> > import System.IO  
>> > import Control.Monad
>> >
>> > main = do
>> >   file <- readFile "hello.txt"
>> >   forM_ [5..7] (lines file) \i -> 
>> >       putStrLn i
>> 
>> Did you mean
>> 
>>   forM_ (lines file) (\i -> putStrLn i)
>> 
>> ?  The syntax error is that you need ()s round the lambda expression
>> here, but the extra list [5..7] is puzzling me.
>
> would like to choose specified lines to display

Then replace (lines file) with an expression that gives the lines you
want.  For example (take 2 (drop 4 (lines file)))  (which is neater
using $ but that's not the point).

-- 
Ben.

Back to comp.lang.haskell | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

parse error on input when print specified lines of a file meInvent bbird <jobmattcon@gmail.com> - 2016-08-23 01:52 -0700
  Re: parse error on input when print specified lines of a file Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-23 11:00 +0100
    Re: parse error on input when print specified lines of a file meInvent bbird <jobmattcon@gmail.com> - 2016-08-23 18:40 -0700
      Re: parse error on input when print specified lines of a file meInvent bbird <jobmattcon@gmail.com> - 2016-08-23 18:49 -0700
      Re: parse error on input when print specified lines of a file Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-24 10:07 +0100

csiph-web