Re: [Haskell-cafe] Why is there no splitSeperator function inData.List
On Sun, Feb 13, 2011 at 11:33:16PM -0800, Donn Cave wrote:
It is curious though that the Python community managed to agree on a
single implementation and include that in the standard library
To me, it's more like 2 implementations, overloaded on the same
function name.
Python 2.6.2 (r262:71600, Aug 30 2009, 15:41:32)
[GCC 2.95.3-haiku-090629] on haiku1
Type help, copyright, credits or license for more information.
import string
string.split(' ho ho ')
['ho', 'ho']
string.split(' ho ho ', ' ')
['', 'ho', 'ho', '']
I.e., let the separator parameter default (to whitespace), and you
get what we have with Prelude.words, but specify a split character
and you get a reversible split. It wasn't a new idea, the Bourne
shell for example has a similar dual semantics depending on whether
the separator is white space or not. Somehow doesn't seem right
for Haskell, though.
Agreed, but I don't think that lacking a generic split functionality (as
in reversible split) is also good.
iustin
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Re: [Haskell-cafe] Why is there no splitSeperator function inData.List
Quoth Peter Simons sim...@cryp.to, ... having a dictator is not a necessary prerequisite for the ability to make decisions. It's quite possible to decide controversial matters without a dictator -- say, by letting people vote. The problem might be slightly miscast here, as an inability to reach a decision in the face of controversy, and overall I don't think you could make much of a case that Python's development is noticeably more decisive. If you really have 8 candidates for the semantics of separator-split, then even if everyone can bring themselves to agree on one, it's still just one, out of 8 missing functions, and it's fairly understandable that this might not be very appealing. Python also - is different in that function semantics can be conveniently overloaded (I forgot the count parameter, I often want that one - split at the first (n - 1) locations and leave the remainder intact) - is different as a general matter of style and niche - doesn't have our division between String and ByteString - makes it harder and more expensive to implement string.split() Anyway, before it gets to the point where the crowds are camping in the city square and demanding a vote, it might be interesting to see where the code comes down on the matter, so I looked at the hackage source I already happen to have at hand, a measly 252 Haskell source files. I found one (1) separator-split implementation. I was surprised at so few, as I've done it myself several times, so maybe I happen to have an unrepresentative sample? Donn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why is there no splitSeperator function inData.List
It is curious though that the Python community managed to agree on a
single implementation and include that in the standard library
To me, it's more like 2 implementations, overloaded on the same
function name.
Python 2.6.2 (r262:71600, Aug 30 2009, 15:41:32)
[GCC 2.95.3-haiku-090629] on haiku1
Type help, copyright, credits or license for more information.
import string
string.split(' ho ho ')
['ho', 'ho']
string.split(' ho ho ', ' ')
['', 'ho', 'ho', '']
I.e., let the separator parameter default (to whitespace), and you
get what we have with Prelude.words, but specify a split character
and you get a reversible split. It wasn't a new idea, the Bourne
shell for example has a similar dual semantics depending on whether
the separator is white space or not. Somehow doesn't seem right
for Haskell, though.
Donn Cave
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