Re: [Haskell-cafe] groupBy huh?

2011-03-07 Thread Henning Thielemann
Jacek Generowicz schrieb: > Hi Cafe, > > It seems that I don't understand what groupBy does. > > I expect it to group together elements as long as adjacent ones satisfy > the predicate, so I would expect ALL four of the following to give one > group of 3 and a group of 1. > > Prelude> :m + Data.

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread Jacek Generowicz
On 2011 Mar 4, at 02:14, Brandon S Allbery KF8NH wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 3/3/11 20:09 , Jacek Generowicz wrote: 1 < 2 ok, same group 1 < 3 dito 1 < 2 dito Thus you get [[1,2,3,2]] OK, that works, but it seems like a strange choice ... Stability is often val

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread wren ng thornton
On 3/3/11 8:14 PM, Brandon S Allbery KF8NH wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 3/3/11 20:09 , Jacek Generowicz wrote: 1< 2 ok, same group 1< 3 dito 1< 2 dito Thus you get [[1,2,3,2]] OK, that works, but it seems like a strange choice ... Stability is often valued in f

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread wren ng thornton
On 3/3/11 7:18 PM, Jacek Generowicz wrote: Hi Cafe, It seems that I don't understand what groupBy does. I expect it to group together elements as long as adjacent ones satisfy the predicate, so I would expect ALL four of the following to give one group of 3 and a group of 1. Prelude> :m + Data

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread Joachim Breitner
Hi, Am Freitag, den 04.03.2011, 01:18 +0100 schrieb Jacek Generowicz: > It seems that I don't understand what groupBy does. > > I expect it to group together elements as long as adjacent ones > satisfy the predicate, so I would expect ALL four of the following to > give one group of 3 and a g

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread Brandon S Allbery KF8NH
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 3/3/11 20:09 , Jacek Generowicz wrote: >> 1 < 2 ok, same group >> 1 < 3 dito >> 1 < 2 dito >> Thus you get [[1,2,3,2]] > > OK, that works, but it seems like a strange choice ... Stability is often valued in functions like this: the order of eleme

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread Jacek Generowicz
On 2011 Mar 4, at 01:39, Marc Weber wrote: Excerpts from Jacek Generowicz's message of Fri Mar 04 00:18:07 + 2011: Prelude Data.List> groupBy (<) [1,2,3,2] [[1,2,3,2]] This is wired. However if you think about the algorithm always using the first element of a list and comparing it again

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread Daniel Fischer
On Friday 04 March 2011 01:18:07, Jacek Generowicz wrote: > Hi Cafe, > > It seems that I don't understand what groupBy does. > > I expect it to group together elements as long as adjacent ones > satisfy the predicate, so I would expect ALL four of the following to > give one group of 3 and a grou

Re: [Haskell-cafe] groupBy huh?

2011-03-03 Thread Marc Weber
Excerpts from Jacek Generowicz's message of Fri Mar 04 00:18:07 + 2011: > Prelude Data.List> groupBy (<) [1,2,3,2] > [[1,2,3,2]] This is wired. However if you think about the algorithm always using the first element of a list and comparing it against the next elements you get 1 < 2 ok, same gr

[Haskell-cafe] groupBy huh?

2011-03-03 Thread Jacek Generowicz
Hi Cafe, It seems that I don't understand what groupBy does. I expect it to group together elements as long as adjacent ones satisfy the predicate, so I would expect ALL four of the following to give one group of 3 and a group of 1. Prelude> :m + Data.List Prelude Data.List> groupBy (<) "a