haskell - Why does `take` with a large number return [] even though the list is infinite? -


i have doubt on why haskell couldn't handle following line

prelude> take 1000000000000 $ repeat ' '

that line of code return:

""

which not 1,000,000,000,000 spaces.

if try 1 less zero, print long time.

and thing bothers me if write

prelude> repeat ' '

it work, being lot of more zeros.

so, why couldn't haskell print long time did repeat alone?

are on 32 bit system? suspect 1000000000000 wraps int negative number. it's equal 2^40.

you can check what's going on entering 1000000000000 :: int.

take negative number returns empty list:

prelude> take (- 1) [1,2,3] []

for reference, take takes int:

prelude> :t take take :: int -> [a] -> [a]

Comments

Post a Comment

Popular posts from this blog

.htaccess - First slash is removed after domain when entering a webpage in the browser -

sometimes when hit address of webpage in browser, removes first slash after domain. examples: www.mywebsite.com/scripts/script_6.php -> trying load www.mywebsite.comscripts/script_6.php www.mywebsite.com/test.php -> trying load www.mywebsite.comtest.php after entering again, loads page. a .htaccess settings must wrong: rewritebase / errordocument 404 http://www.mywebsite.com/oops.php errordocument 401 /notallowed.php rewriteengine on # turn on rewriting engine #gzip <ifmodule mod_deflate.c> addoutputfilterbytype deflate text/text text/html text/plain text/xml text/css application/x- javascript application/javascript </ifmodule> #end gzip rewritecond %{http_host} ^mywebsite\.com rewriterule ^(.*)$ http://www.mywebsite.com$1 [r=permanent,l] directoryindex index6.php rewriterule ^termsofuse/?$ termsofuse.php [nc,l] # handle requests "adpolicy" rewriterule ^privacy-policy/?$ privacy-policy.php [nc,l] # handle requ...
Read more

Socket.connect doesn't throw exception in Android -

if put nonsense url no exception thrown , none of rest of code executed not rest of asynctask called method connects. try { socketcliente.connect(new inetsocketaddress("f", port), 2000); } catch (unknownhostexception e) { geterror("host doesn't exist"); return -1; } catch (ioexception e) { geterror("could not connect: host down"); return -1; } add catch statement. catch ( exception e ) { log.d(tag, e.getmessage(),e); toast.maketext(getapplicationcontext(), "unexpected error:" + e.getmessage(), toast.length_long).show(); } this write log , pop toast tell what's going on.
Read more

SPSS keyboard combination alters encoding -

my question not have programming practical issue on spss. accident keyword combination cannot remember because did not intend press changed encoding in spss , text in data in different language english shown small boxes. nevertheless, when kind of analysis performed different language text shown in output. does know reason? tried change encoding did not produce result. first, @ edit > options , see whether setting unicode or locale. might fix it. if have text in multiple languages, want unicode. otherwise, may have specific locale set wrong. can change set locale, need know locale want use.
Read more