Re: [Lift] Re: Scala to JavaScript DSL ...
Inlined
2009/12/19 Marius marius.dan...@gmail.com
If I may a few notes:
Syntactically it doesn't seem to me that there are much differences
between this and the initial proposal. Probably the most noticeable
diffs are in algebraic expressions like
Var(y) := (2:Expr) * x * 2
which probably looks more appealing than
Var(y) := 2 __* x __* 2
First, I should confess that I didn't look at your source code before I
wrote my approach, although I saw it now. That said, I agree that there is
plenty in common between the two approaches, and also a couple of
differences. Feel free to use whatever blend you like!
The other thing is that you don't end JS statements with ; ... I
don't think this is a good JS practice. I added `;` function to allow
user to specify this terminator when needed.
It would be trivial to have my implementation add semicolons in the
generated code without requiring any change in the DSL's usage.
I'm also not at all in favor of function names starting with capital
letter.
Please rename them to whatever you like!
I was also running into a Scala compiler crash when using constructs
like: case class Fnc(name: String)(params: String*)(body : = String)
{} :D
Then possibly functions are better suited than case classes for providing
the names of the DSL syntax. If that means you prefer lowercase names please
change them!
I'm not sure why in things like: def Function()(argNames: String*)
(body: PartialFunction[List[JSIdent], Unit]): JSAnonFunc you used
PartialFunctions ... you are callin gthe PF without checking if the
function is defined for its parameter which could lead to MachError.
What would it help to intercept such a situation--to provide a more
descriptive error message? It's an error either way.
In any case, I realized after I wrote it (as I mentioned) that the signature
could be changed to
def Function(numParams: Int)(body: PartialFunction[List[JSIdent], Unit])
that is, there is no reason to specify names for the parameters. Since the
PF format binds scala identifiers to represent the arguments, names could be
autogenerated. Similarly,
val x = Var(x)
could be changed to
val x = Var()
and x would represent a JS var whose name is autogenerated.
I could be totally wrong but it seems to me that the ability to have Scala
identifiers and not just implicitly converted symbols provides more
scalability. For instance you could have utility functions in Scala that
help build the javascript but don't need the implicits in scope.
I see you took a different approach of building JS code in a more
imperative manner where generated code is kept in the ThreadGlobal
state. My initial approach and actually my design intent was to use
functional composition to write the code which tremendously simplifies
the library code.
Could you elaborate? What makes your code more functional?
With your approach,
JsIf('param1 30) {
Var ('home) := (234: Js) + 3 / 3 `;`
println(Hi there)
Var ('someArray) := JsArray(1, 2, 3, 4, 5) `;`
'myFunc(1, 2, do it, 'home) `;`
$(#myID) 'attr(value, 123) `;`
} ~
would not work, because JsIf's second parameter list takes a =Js, that is,
it only uses on the expression returned. In the above example, the
Var('home) ... line goes into a black hole.
In my case you have much more flexibility because the entire code block does
not have to be one long expression. All DSL invocations are captured.
This is also the reason my approach does not require using semicolons.
Also, it would be advantageous if the result of executing the DSL was the
regular Lift JavaScript AST. This would avoid code duplication in terms of
the algorithm that generates the output javascript text (which if it does
not already could have shared features like whitespace compression or pretty
printing), while at the same time allowing the generated AST to be processed
by code that can also work with plain Lift JavaScript AST objects. I'm not
clear how that would work with your approach, but with mine it's trivial.
I should mention that much of the inspiration for this builder approach came
from the SWT DSL, by Rodant.
I made some adjustments to my initial approach and something like:
val js = JsFunc('myFunc, 'param1, 'param2) {
JsIf('param1 30) {
Var ('home) := (234: Js) + 3 / 3 `;`
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)
generates
function myFunc( param1, param2 ) {
if (param1 30) {
var home = 234 + 3 / 3;
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 (
Re: [Lift] Re: Scala to JavaScript DSL ...
I think I'm nearly there (that is a working equivalent of your sample) with
G-d's help...
-
Mariusmarius.dan...@gmail.com wrote:
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 Danciumarius.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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Re: [Lift] Re: Scala to JavaScript DSL ...
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 Danciumarius.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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DSL.scala
Description: Binary data
Re: [Lift] Re: Scala to JavaScript DSL ...
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 Danciumarius.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
Re: [Lift] Re: Scala to JavaScript DSL ...
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 Danciumarius.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
Re: [Lift] Re: Scala to JavaScript DSL ...
You're welcome. There's still some work to do; I would call it a proof of
concept. But I'll let Marius finish it up. :)
On Thu, Dec 17, 2009 at 10:18 PM, Ross Mellgren dri...@gmail.com wrote:
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 Danciumarius.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
Re: [Lift] Re: Scala to JavaScript DSL ...
Other advantages of a DSL include type safety and typo safety. :)
-
Mariusmarius.dan...@gmail.com wrote:
That is certainly one way to go but personally I'm not at all a fan of
this string literals approach,. For instance if Scala would not have
had built in XML support using XML as string literals Lift would
probably loose some of its attractions... but that's my opinion.
Furthermore a DSL like language allows better compositionality than
concatenating strings when we want to iteratively add JS code ... for
instance calling the same function multiple times with different
arguments, or collecting code fragments generated by different
application components etc.
Also it seems to me that your approach (somehow similar with
Velocity's) is more expensive but I admit that this is not at all a
strong argument because we're talking about small javascript fragments
so the delta is negligible.
Br's,
Marius
On Dec 12, 8:42 pm, Alex Boisvert alex.boisv...@gmail.com wrote:
Personally, I would rather go with a JavaScript literal and a simple
templating mechanism for substitution/binding of Javascript literals + Json
objects that would drive dynamic code (if conditionals, for-loops, ...).
Taking your example,
def myFunc = {
function myFunc( param1, param2 ) {
if (param1 ${limit}) {
var home = ( ${max} - 3 ) / 2;
var someArray = ${array};
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);
}.jsBind(
max - max,
array - array,
someArray - someArray,
...
)
Not a fully fleshed out example but you get the idea. You'd still be able
to bind existing JsExp/JsCmds so some parts could still be abstracted and
typed checked.
I would find this more readable and simpler that learning a quirky DSL
syntax. And I could still copy/paste Javascript code to/from the browser
and test it easily.
alex
On Sat, Dec 12, 2009 at 2:07 AM, Marius Danciu marius.dan...@gmail.comwrote:
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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Re: [Lift] Re: Scala to JavaScript DSL ...
On Sat, Dec 12, 2009 at 11:06 AM, Marius marius.dan...@gmail.com wrote: That is certainly one way to go but personally I'm not at all a fan of this string literals approach,. For instance if Scala would not have had built in XML support using XML as string literals Lift would probably loose some of its attractions... but that's my opinion. Agreed, XML is baked-in. It's not a DSL built on top of other features. Furthermore a DSL like language allows better compositionality than concatenating strings when we want to iteratively add JS code ... for instance calling the same function multiple times with different arguments, or collecting code fragments generated by different application components etc. There's no guarantee of compositionality for DSLs. You have to design it to be, and it's quite difficult to get right. And then you pretty much reinvent another language. First you have Scala, then you have Javascript, then you have something in between which is FrankenScalaScript.Just my opinion :) Also it seems to me that your approach (somehow similar with Velocity's) is more expensive but I admit that this is not at all a strong argument because we're talking about small javascript fragments so the delta is negligible. I would beg to differ but we're so far from any implementation of either to judge performance at this stage. alex -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
Re: [Lift] Re: Scala to JavaScript DSL ...
On 12/12/09 4:39 PM, Marius wrote:
My notes inline.
On Dec 12, 12:34 pm, Timothy Perretttimo...@getintheloop.eu wrote:
Hey Marius,
Within this DSL will you be using JsObj under the hood or lift-json?
I was thinking to use lift-json in this case ... but I'd also of
prefer having a lift-js project.
I would be very reluctant about adding new things to lift that don't
unify our Js and JSON libs.
Depends what you mean by unify. lift-json is not the same with js
support, js should utilize lift-json to build json constructs being
part of the javascript generated but lift-json has nothing to to with
a potential lift-js project. Therefore I would keep lift-json and lift-
js separated and have lift-js utilize lift-json whenever possible.
I would be hugely in favor of lift-js. I see lift-json deal with the
data container related functionality. This would be clearly demarcated
from lift-js (the scripting, method calls etc.) that is primarily used
for deeper framework level integration for building (mostly web)
applications.
In that sense, lift-webkit could also shed some weight in favor of
lift-js (parts of net.liftweb.http.js, for example). On one hand we
would have a neatly composed package with focused purpose and on the
other hand lift-webkit would feel 'lighter' to projects that don't need
any of the js functionality at all.
The dependency tree could look like (lower components depend on one or
more above them):
lift-common
lift-actor [1]
lift-json [1]
lift-util [2]
lift-js [2]
lift-webkit [3]
[1] Independent of each other currently.
[2] Can interchange depending on how things go.
[3] In some sense lift-webkit still ends up depending on lift-js
transitively. But that's better than 2.7M monolith :) It can even create
opportunity for marking lift-js as 'optional dependency' for lift-webkit.
In any case, this is a derived profit and doesn't have to be the primary
goal.
On this note, will this unification take place before 2.0?
Too soon to tell. I'm not sure yet if people like this proposal so we
first need acceptance and then talk schedules.
Cheers, Tim
Sent from my iPhone
On 12 Dec 2009, at 10:07, Marius Danciumarius.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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