On 21-10-10 01:01, Victor Nazarov wrote:
I've been working on this for some month and I think now I'm ready to
share the results.
Great stuff! I've been looking for something like this for a long time.
If you add "|| transport.status == 0" to line 90 of
examples/rts-common.js, it also works on a local file system.
I played around with it a bit to see how easy it was to call JavaScript
from Haskell, and it turned out to be straightforward. With a little
guessing, I constructed a JavaScript representation of a thunk, which
evaluates its string argument as a JavaScript expression and returns the
resulting string to Haskell. This thunk can be passed to the
JavaScript-compiled Haskell function. To pass it around in Haskell and
force its evaluation, I constructed a simple monad.
Now, on your web page, you can do something like:
<input type="text" onkeyup="execHaskell('validate')" id="inputField"/>
and in a Haskell module:
validate :: JS ()
validate =
do { inputValue <- eval "document.getElementById('inputField').value"
; exec $
"document.getElementById('inputField').style.backgroundColor="++
color inputValue
}
where color str = if and (map isDigit str) then "'white'" else "'red'"
This example creates a text field that turns red if it contains any
non-digit characters. It is on-line at
http://tryout.oblomov.com/ghcjs/ghcjs.html (Note: I only tested it on
Firefox on a Mac)
All used files are in a zip file at
http://tryout.oblomov.com/ghcjs/ghcjs.zip (validate is in Test.hs, the
JS monad in JS.hs, and the JavaScript for execHaskell in util.js)
Cheers,
Martijn Schrage -- Oblomov Systems
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