I like the source for the DSL very much, I think it's very well written. Thanks
for sharing it.
-Ross
On Dec 17, 2009, at 9:34 PM, Naftoli Gugenheim wrote:
> Okay!
> The following code:
> val jsFunc: JSFunc = Function("myFunc")("param1", "param2") {case param1
> :: param2 :: Nil =>
> Var("someArray") := Array(1, 2, 3, 4, 5)
> If(param1 < 30) {
> val x = Var("x") // now we can use either x or 'x
> x := (234 - 3) / 2 // calculation happens in scala
> Var("y") := (2:Expr) * x * 2 // calculation happens in javascript
> 'jsFunc(1, 2, "do it", 'y)
> val $ = JSIdent("$")
> $("#myID") >> 'attr("value", "123")
> } Else {
> 'console >> 'log(">=30")
> }
> ForEach(Var("i") In 'someArray) {
> 'console >> 'log("Hi there " & 'i)
> }
> Function()("arg1", "arg2") { case arg1 :: arg2 :: Nil =>
> 'alert("Anonymous function (" & arg1 & ", " & arg2 & ")")
> }(1,2)
> }
> println(jsFunc.toCode)
>
> Produces:
>
> function myFunc(param1, param2) {
> var someArray
> someArray = [1.0, 2.0, 3.0, 4.0, 5.0]
> if((param1 < 30.0)) {
> var x
> x = 115.0
> var y
> y = ((2.0 * x) * 2.0)
> jsFunc(1.0, 2.0, "do it", y)
> ($("#myID")).attr("value", "123")
> } else {
> (console).log(">=30")
> }
> var i
> for(i in someArray) {
> (console).log(("Hi there " + i))
> }
> function (arg1, arg2) {
> alert((((("Anonymous function (" + arg1) + ", ") & arg2) + ")"))
> }(1.0, 2.0)
> }
>
> It may be desirable that instead of defining your own names for Vars and
> function parameters, names are auto-generated, since you can anyway use
> typesafe scala identifiers. This would save boilerplate and produce more
> "obfuscated" code, and other than the name generating algorithm is a trivial
> change to make.
> Note that since I am not familiar with Lift's JavaScript APIs I just wrote my
> own AST, which consists of case classes that contain their data parameters
> and a toCode method. Feel free to delete them and plug Lift's classes
> instead--there is no dependency on anything unique about them.
> Also note that to prevent "string" + ident from compiling as a string to be
> outputted and instead output a + operation, you have two choices: use the &
> operator instead, which is replaced with + when either operand is a string,
> or write ("string":Expr) + ident.
>
>
> 2009/12/17 Naftoli Gugenheim <naftoli...@gmail.com>
> Current state attached.
>
>
> 2009/12/17 Marius <marius.dan...@gmail.com>
>
> Let me know when you have something.
>
> Br's,
> Marius
>
> On Dec 17, 8:58 am, Naftoli Gugenheim <naftoli...@gmail.com> wrote:
> > I'm thinking of an approach to writing a DSL with a much cleaner syntax.
> > I'll try to put something together.
> >
> > -------------------------------------
> >
> > Marius Danciu<marius.dan...@gmail.com> wrote:
> >
> > All,
> >
> > I just want to see if there is any interest in the approach discussed here.
> > As you know Lift has some interesting support for building JavaScript
> > constructs from Scala code usig JsExp, JsCmd etc classes. I used quite a lot
> > this support and it's great but if your JS code that you want to send down
> > to the browser (say as an Ajax or Comet partial update response) gets a bit
> > more complicated then constructing the JS fragment leads IMO to some
> > cumbersome Scala code. I found myselft in quite a few situation to use JsRaw
> > to write the JavaScript fragment in order for the code reader to understand
> > what JavaScript code will be generated. But of course with JsRaw we put
> > everything into a String so I'm not a big fan of this approach. So I started
> > to define a JavaScript like "DSL" that IMO is closer to JavaScript form.
> > Attached is a source code smaple of how this looks like, so for instance we
> > can have something like:
> >
> > val js = JsFunc('myFunc, 'param1, 'param2) {
> > JsIf('param1 __< 30) {
> > Var('home) := Wrap(234 __- 3) __/ 2 `;`
> > Var('someArray) := JsArray(1, 2, 3, 4, 5) `;`
> > 'myFunc(1, 2, "do it", 'home) `;`
> > $("#myID") >> 'attr("value", "123") `;`
> > } ~
> > JsForEach(Var('i) in 'someArray) {
> > 'console >> 'log("Hi there " __+ 'i) `;`
> > } ~
> > JsAnonFunc('arg1, 'arg2) {
> > 'alert("Anonymous function " __+ 'arg1 __+ 'arg2)
> > }(1, 2) `;`
> > }
> >
> > println(js.toJs)
> >
> > this yields the following JavaScript code:
> >
> > function myFunc( param1, param2 ) {
> > if (param1 < 30) {
> > var home = ( 234 - 3 ) / 2;
> > var someArray = [ 1, 2, 3, 4, 5 ];
> > myFunc(1, 2, "do it", home);
> > $("#myID").attr("value", "123");}
> >
> > for (var i in someArray) {
> > console.log("Hi there " + i);}
> >
> > function ( arg1, arg2 ) {
> > alert("Anonymous function " + arg1 + arg2)
> >
> > }(1, 2);
> > }
> >
> > ... ok I just droped nonsense code in there for exemplification. A few
> > words:
> >
> > 1. JsIf, JsForEach describe JavaScript if and for(each) statements
> > 2. Functions like __<, __>, ... __+, __- are function that alows definition
> > of boolean and/or algebraic expressions.
> > 3. Wrap just wraps an expression into ()
> > 4. Var defined a variable
> > 5 := defines an assignment
> > 6. JsFunc declares a JS function
> > 7. JsAnonFunc declares an anonymous function
> > 8. 'myFunc(1, 2, "do it", 'home) is simply a javascript function invocation
> > by providing 4 parameter.
> > 9. ~ is just a function that chains statements that don;t necessarily end in
> > ;
> >
> > Do you think that something like this would be usable in Lift?
> >
> > Br's,
> > Marius
> >
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