Fear uncertainty and doubt

[Sonia Keys]

Some recent comments on Stack Overflow are bugging me.  I'm asking for help here because the comments have the effect of spreading FUD about Go.  The posted question asks how to create a case insensitive map.  The troublesome comments make false statements about Go's handling of Unicode (when the OP wasn't even concerned with Unicode.)  Correcting this person would seem to be accepting their challenge to an off-topic flame war.  Instead, I would encourage anyone with a SO account to flag these comments for moderation.  Note that on the flag dialog, while the "off-topic or unconstructive" radio button is appropriate, the "other" button allows you to send a message to moderators explaining what you feel is wrong with the comments.

[Matt Kane's Brain]

I don't see any anti-Go FUD. Did something get deleted?

--
matt kane's brain
http://hydrogenproject.com

[Aram Hăvărneanu]

FUD on the Internet? Preposterous!

--
Aram Hăvărneanu

[roger peppe]

On 21 June 2012 15:00, Sonia Keys <soni...@gmail.com> wrote:
> Some recent comments on Stack Overflow are bugging me.  I'm asking for help
> here because the comments have the effect of spreading FUD about Go.  The
> posted question asks how to create a case insensitive map.  The troublesome
> comments make false statements about Go's handling of Unicode (when the OP
> wasn't even concerned with Unicode.)

The comments seem reasonable to me. It's correct that you can't
do a case insensitive map that works correctly with unicode characters
by using strings.ToLower. That's the reason that strings.EqualFold
exists.

I wonder if using strings.Map(unicode.SimpleFold, s) would be wrong
too. Unicode is too subtle for me...

[Matt Kane's Brain]

On Thu, Jun 21, 2012 at 10:25 AM, roger peppe <rogp...@gmail.com> wrote:
> I wonder if using strings.Map(unicode.SimpleFold, s) would be wrong
> too. Unicode is too subtle for me...

It doesn't look like that's quite right. unicode.SimpleFold is
intended to iterate through all cases. I think you need a wrapper
function around SimpleFold like this:

func Fold(r rune) (s rune) {
for {
s = unicode.SimpleFold(r)
if s <= r {
return
} else {
r = s
}
}
panic("unreachable")

[Sonia Keys]

So Unicode case folding might be an interesting question.  The OP there wasn't asking that question.  strings.  The comments assert that strings.ToLower only works for ASCII, which at a casual glance at source is not true.  I see return Map(unicode.ToLower, s), which seems to be doing at least something Unicode aware.

On Thursday, June 21, 2012 10:37:54 AM UTC-4, mkb wrote:

[peterGo]

Sonia,

Read The Unicode Standard and other Unicode documentation.
http://unicode.org/

Peter

On Jun 21, 10:00 am, Sonia Keys <soniak...@gmail.com> wrote:
> Some recent comments on Stack Overflow are bugging me.  I'm asking for help
> here because the comments have the effect of spreading FUD about Go.  The

> posted question<http://stackoverflow.com/questions/11124705/how-to-create-a-case-inse...>asks how to create a case insensitive map.  The troublesome comments make

[Patrick Mylund Nielsen]

ToLower works just fine for Unicode strings, there will just be "collisions" because it's not as simple as "upper" or "lower", which is what I assume tchrist was referring to when he said it "didn't work for Unicode strings" (in hash tables)

[Paul Borman]

Unicode doesn't even always have a single encoding for the same string.  There is an entire section of unicode dedicated to producing canonical strings.  This would be important when using as a key to a map.  I think this is way beyond what most people think of when they say "case insensitive".

    -Paul

[⚛]

On Thursday, June 21, 2012 4:00:48 PM UTC+2, Sonia Keys wrote:

Some recent comments on Stack Overflow are bugging me.  I'm asking for help here because the comments have the effect of spreading FUD about Go.  The posted question asks how to create a case insensitive map.  The troublesome comments make false statements about Go's handling of Unicode (when the OP wasn't even concerned with Unicode.)  Correcting this person would seem to be accepting their challenge to an off-topic flame war.  Instead, I would encourage anyone with a SO account to flag these comments for moderation.  Note that on the flag dialog, while the "off-topic or unconstructive" radio button is appropriate, the "other" button allows you to send a message to moderators explaining what you feel is wrong with the comments.

The author of the questionable comments on Stack Overflow (tchrist) is right, but he overreacted. It was incorrect to start his reply with "This is completely wrong", the correct form is "You are right, but [mention some improvements here]".

Aside from this, "godoc unicode" says that:

    There is no mechanism for full case folding, that is, for characters

    that involve multiple runes in the input or output.

[Patrick Mylund Nielsen]

Then the question becomes if it's relevant for most maps, but given that it's a "case-insensitive map", it's probably likely to use user-supplied keys, in which case it really is, and restricting to ASCII might be the easiest solution.

[Andy Balholm]

Before you call this comment FUD about Go, you should see what tchrist has to say about unicode support in Perl, his favorite language:

http://stackoverflow.com/questions/6162484/why-does-modern-perl-avoid-utf-8-by-default/6163129#6163129

P.S. I recommend installing the Symbola font and viewing his post in Firefox. His post itself requires better Unicode support than some browsers have.

[Patrick Mylund Nielsen]

That's actually really good.

PS: I'm not Sonia, but I think the "FUD" was that he claimed that ToLower "doesn't work" for Unicode strings/characters, which clearly isn't correct in Go. It just doesn't work how you might expect--rather, in a way that is undesirable for the hash table key use case. This post was a better (and less condescending) explanation why.

[Sonia Keys]

Thanks to all for interesting comments and education.  It looks like someday the good answer will be something like Collate.Key, currently in exp/locale/collate.  Is this right?

[Andy Balholm]

That would actually go beyond case-insensitivity, but it might be what most of the people who ask for case-insensitivity actually need.

[Rob 'Commander' Pike]

On Thu, Jun 21, 2012 at 3:43 PM, <tch...@perl.com> wrote:
> The world is not ASCII any longer.

It never was.

-rob