Re: [web-devel] [Yesod] rendering different templates for different languages

21 Feb 2011

      The other day I was speaking with a woman on the train. She was
telling me about her daughters. I wanted to ask her how old they are,
but I got the pluralization wrong and instead of saying "bnot kama"
(plural) I said "bat kama," (singular) to which she responded 36.

tl;dr: You can offend people just was well with pluralization issues
as with gender issues.

Michael

On Mon, Feb 21, 2011 at 8:40 AM, Max Cantor  wrote:
...
Of course, you just pointed out one of the big difficulties with i18n.  I dont think you're wife would take kindly to you referring to her in the male gender.  so now, you need the person's gender too.  i18n is hard :(  the whole would should switch to esperanto.
max
On Feb 21, 2011, at 2:25 PM, Michael Snoyman wrote:
...
A proper i18n solution is high on my wish list right now, but I've
purposely avoided implementing one so far since I'd rather wait until
I think we have a good solution as opposed to implementing an
acceptable solution now. But let me share my ideas, it might help you
out here.
In general, it's very uncommon that you need a completely separate set
of templates for each language. Your markup, classes, styles, and
logic will likely be identical for each language, and creating a
separate template for each will just result in a lot of pain in the
long run. Instead, you're likely better off having a single template
and just translating strings.
I've blogged about this before[1]. My idea is to use a datatype for
your translatable strings, and then have a function that takes a
language and a value and returns the translated string. A simple
example:
   data Strings = Hello | Person String Int
   toEnglish Hello = "Hello"
   toEnglish (Person name age) = name ++ " is " ++ show age ++ "
years old" -- obviously need to check if person is 1 year old and
correct
   toHebrew Hello = "שלום"
   toHebrew (Person name age) = name ++ " הוא בן " ++ show age ++ " שנים"
The nice thing about this approach is you have the full power of
Haskell to address typical translation issues, such as pluralization,
word order and gender matching. (As a counter example, at work, we use
XSLT for this, and then you get the full power of XSLT for solving the
problem ::cringe::.)
You can then use the languages[2] function from Yesod to help you out:
   getRenderString = chooseFunc `fmap` languages
      where
        chooseFunc [] = toEnglish -- default language
        chooseFunc ("en":_) = toEnglish
        chooseFunc ("he":_) = toHebrew
        chooseFunc (_:x) = chooseFunc x
Then you can write a handler function like:
getPersonR name age = do
   render <- getRenderString
   defaultLayout [$hamlet|
<h1>#{render Hello}
<p>#{render $ Person name age}
|]
Which will work for English and Hebrew just fine. Ideally, I would
like to add support to Hamlet for this directly, involving a String
rendering function similar to the URL rendering function already in
place. But for the moment, this should work.
I'd love to hear peoples opinions about this.
Michael
[1] http://docs.yesodweb.com/blog/i18n-in-haskell
[2] http://hackage.haskell.org/packages/archive/yesod-core/0.7.0.1/doc/html/Yeso...
On Sun, Feb 20, 2011 at 11:19 PM, Dmitry Kurochkin
 wrote:
...
Hi all.
I want a handler to render different templates for different languages.
I have getCurrentLanguage function and now I try to do something like:
   getRootR = do
       currentLanguage <- getCurrentLanguage
       defaultLayout $ do
           addWidget $(widgetFile $ currentLanguage ++ "/homepage")
This results in:
   GHC stage restriction: `currentLanguage'
     is used in a top-level splice or annotation,
     and must be imported, not defined locally
This makes sense to me, because TH is calculated at compile time. I
would like to hear ideas how to work around this restriction. Perhaps
there is an existing solution in Yesod?
At the moment, the best I could think of is smth like this:
   getRootR = do
       currentLanguage <- getCurrentLanguage
       defaultLayout $ do
           case currentLanguage of
               "en" -> addWidget $(widgetFile  "en/homepage")
               ... and so on for each language ...
Obviously, this is not a solution taking in account that there are many
languages and many handlers.
I was considering creating a global (template file name -> rendered
template) map. But I am not sure this is really feasible.
Regards,
 Dmitry
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