Re: [Haskell-cafe] Comma in the front
Tim Docker wrote: These layouts feel a bit artificial to me. I am quite partial to python's list syntax - a trailing comma is optional. meaning you can write [ a, b, c, ] I'm surprised this approach isn't more widespread - Are there reasons why haskell syntax could not/should not be defined this way? I think this would be confusing because it looks like a syntax error - the last element is missing. The advantage of just having comma as a separator is that it allows syntax errors to be detected, whereas making it optional would mean one less error is detected at compile time. I'll take this opportunity to re-present my hyper-cool syntax proposal for lists ;-) : #[ a b c No need for commas or a closing ] because we could just use layout! Regards, Brian. -- Logic empowers us and Love gives us purpose. Yet still phantoms restless for eras long past, congealed in the present in unthought forms, strive mightily unseen to destroy us. http://www.metamilk.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comma in the front
On 2006-07-13 at 02:29BST Neil Mitchell wrote: Hi, Are cool kids supposed to put the comma in front like this? Some cool kids do, some cool kids don't. Some do both, depending on their mood. The advantage of a leading , is that now the comma's line up, and if you want to add an item on the end of a list [a ,b ,c ] It's just a one line change, whereas with the comma after, you'd have to change the previous line as well - which is more effort and gives more noise in the darcs copy. This is one of my pet hates. First, people find things easier to read if they are in a form that they have encountered lots of times before (in addition to psycho-visual factors). I'd like to think that Haskell programmers read a lot of literature (and since they should have started reading this long before they learnt to programme, and continue so to read, they're going to have read more literature than code). So for me (and anyone else moderately literate) a list written [a, b, c ] is easier to read and, (for folk who read from left to right) gives emphasis to the important parts rather than the punctuation. (Of course, a list with elements that short would just be written [a, b, c] anyway.) Now, you argue that it's more effort to add (or delete) items from lists in this form, and maybe you are right (I do it by dragging my mouse over stuff I want to remove, so start with the comma and go down; it doesn't seem too hard. If you want keystroke commands, you want something that respects the syntax). The thing is, making modifications that change the meaning /ought/ to be effortful. If you can delete things without thinking about it, you're probably going to delete something you shouldn't. Then the argument from darcs -- well, historically diff is line based, which was fine in the days of punch-cards, but makes much less sense nowadays. Ideally the diff darcs uses should be syntax driven -- a nice project for someone; we can save effort by only doing this for Haskell, and leave programmers in other languages stuck with line-by-line diffs. Jón -- Jón Fairbairn Jon.Fairbairn at cl.cam.ac.uk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comma in the front
On Thu, 13 Jul 2006, Jon Fairbairn wrote: On 2006-07-13 at 02:29BST Neil Mitchell wrote: Hi, Are cool kids supposed to put the comma in front like this? Some cool kids do, some cool kids don't. Some do both, depending on their mood. The advantage of a leading , is that now the comma's line up, and if you want to add an item on the end of a list [a ,b ,c ] It's just a one line change, whereas with the comma after, you'd have to change the previous line as well - which is more effort and gives more noise in the darcs copy. This is one of my pet hates. First, people find things easier to read if they are in a form that they have encountered lots of times before (in addition to psycho-visual factors). I'd like to think that Haskell programmers read a lot of literature (and since they should have started reading this long before they learnt to programme, and continue so to read, they're going to have read more literature than code). So for me (and anyone else moderately literate) a list written [a, b, c ] Optimal notation of lists, because of most easiest editing, is a: b: c: [] =B-] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comma in the front
On 2006-07-13 at 11:15+0200 Henning Thielemann wrote: Optimal notation of lists, because of most easiest editing, is a: b: c: [] That made me smile. In Ponder I had used up : for types, and lists could be a:: b:: c:. but when I suggested this at a Haskell meeting, Simon PJ complained that it looks like hopscotch. I've never quite understood that complaint! Jón -- Jón Fairbairn Jon.Fairbairn at cl.cam.ac.uk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comma in the front
Jon Fairbairn [EMAIL PROTECTED] writes: a:: b:: c:. but when I suggested this at a Haskell meeting, Simon PJ complained that it looks like hopscotch. I've never quite understood that complaint! http://blogs.salon.com/0002296/myimages/hopscotch.jpg and http://www.northshield.org/officers/seneschal/moy/games/hopscotch.gif suggest to me that the pattern of : and . going up in a row is a bit like the squares along the linear 'course' (or list (-:) where sometimes you get one and sometimes two. -- Mark ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comma in the front
On 2006-07-13 at 09:35EDT [EMAIL PROTECTED] (Mark T.B. Carroll) wrote: Jon Fairbairn [EMAIL PROTECTED] writes: a:: b:: c:. but when I suggested this at a Haskell meeting, Simon PJ complained that it looks like hopscotch. I've never quite understood that complaint! http://blogs.salon.com/0002296/myimages/hopscotch.jpg and http://www.northshield.org/officers/seneschal/moy/games/hopscotch.gif suggest to me that the pattern of : and . going up in a row is a bit like the squares along the linear 'course' (or list (-:) where sometimes you get one and sometimes two. Well, perhaps (the pattern I associate with hopscotch is the first, ie ·:·:·:·, which could never happen since :. is the end of the list), but that still leaves open the question What's bad about that? :-) Jón -- Jón Fairbairn Jon.Fairbairn at cl.cam.ac.uk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comma in the front
On Jul 12, 2006, at 9:18 PM, Joel Reymont wrote: Are cool kids supposed to put the comma in front like this? , foo , bar , baz Is this for historical or other reasons because Emacs formats Haskell code well enough regardless. Thanks, Joel I personally like this style. It's a little hard to say why, but let me attempt. I think it's related to layout. Layout trained me to regard the end of lines as uninteresting, and the beginning as interesting. Thus, I forget to put separators at the ends of lines (freedom from the tyranny of the semicolon!), but I always notice if a comma or semicolon is missing at the beginning of a line. Its very obvious because they're all aligned vertically and, as I said, Haskell trains you to notice the leading edges of lines if you use layout. It also makes it very visually obvious where the list/tuple/ do block ends when you line up the brackets with the separators. IMO the patch/diff/darcs issue is a red herring. It sounds like an after the fact justification to me. Rob Dockins Speak softly and drive a Sherman tank. Laugh hard; it's a long way to the bank. -- TMBG ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Comma in the front
On Jul 12, 2006, at 9:18 PM, Joel Reymont wrote: Are cool kids supposed to put the comma in front like this? , foo , bar , baz Is this for historical or other reasons because Emacs formats Haskell code well enough regardless. Thanks, Joel These layouts feel a bit artificial to me. I am quite partial to python's list syntax - a trailing comma is optional. meaning you can write [ a, b, c, ] I'm surprised this approach isn't more widespread - Are there reasons why haskell syntax could not/should not be defined this way? Tim ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comma in the front
On Fri, Jul 14, 2006 at 01:01:23AM +0100, Neil Mitchell wrote: There might be issues with tuples though, for example (1,2,) would be the (,) tuple and not the (,,) tuple, which is a bit weird. Besides, it might be a bit more natural if (1,2,) was a shorthand for (\x - (1,2,x)) Best regards Tomasz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
