[Lift] Re: rlambda lift project updated
Tim, Thanks for your generous offer. Code review would be great. My next steps include - Wiring up BDBXML for a persistence layer - Wiring up ANTLR as the fallback parser generator If you, or anyone, wants to take a swipe at a relational persistence as well, that would be fantastic. The idea is to simply generate the subclasses of the classes in Absyn that would provide the mapping to store. Since i've got a functioning Java parser, i was going to attack the problem at that level. This allows me to generate Scala classes with very little pain. It's also possible to take the following approaches. - Hack the backend of BNFC - Use the visitor pattern stuff generated by BNFC Of course, code review would be great. Also, i just got a note from someone that the jlex/cup dependencies are being properly handled by maven. If you could verify, that would be awesome. Best wishes, --greg On Fri, May 15, 2009 at 4:40 AM, Timothy Perrett timo...@getintheloop.euwrote: Greg, I find this very interesting. How can I help you out here? I can certainly review your lift code, not so sure about some of the crazy conceptual stuff though! Cheers, Tim On May 14, 8:41 pm, Meredith Gregory lgreg.mered...@gmail.com wrote: Lifted, i've added support to the rlambda lift projecthttp://code.google.com/p/rlambda/taking it within range of being a candidate DSL-archetype. At this point it is possible simply to supply a .cf file in the src/main/bnfc directory and it will generate everything from that. i've still got to conditionally include the Eval and Compile functionality for DSL that have/don't have this capability. i've two remaining questions for this leg of the work. - Does anyone know how to reference maven dependencies within some flavor of maven-antrun-plugin? The original version does not appear to have this functionality and Sun's maven-antrun-extended-plugin (which is supposed to supply this functionality) has so little documentation (that i could find) that i couldn't get it to work after an hour our so. - This version requires that BNFC, as an executable, be available on the path. Is there a blessed way to handle this sort of dependency? - i've got a hare-brained scheme that will fix this -- a meta-compiler-compiler from BNFC's input format to ANTLR's. i could include such a transform as a part of the project or a dependency and test for the availability of BNFC and fall back to ANTLR if it's not available. If anybody wanted to give this round of updates a whirl, even give me a code review, i would be very grateful. Best wishes, --greg -- L.G. Meredith Managing Partner Biosimilarity LLC 1219 NW 83rd St Seattle, WA 98117 +1 206.650.3740 http://biosimilarity.blogspot.com -- L.G. Meredith Managing Partner Biosimilarity LLC 1219 NW 83rd St Seattle, WA 98117 +1 206.650.3740 http://biosimilarity.blogspot.com --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to liftweb@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 -~--~~~~--~~--~--~---
[Lift] Re: rlambda lift project updated
Greg, I find this very interesting. How can I help you out here? I can certainly review your lift code, not so sure about some of the crazy conceptual stuff though! Cheers, Tim On May 14, 8:41 pm, Meredith Gregory lgreg.mered...@gmail.com wrote: Lifted, i've added support to the rlambda lift projecthttp://code.google.com/p/rlambda/taking it within range of being a candidate DSL-archetype. At this point it is possible simply to supply a .cf file in the src/main/bnfc directory and it will generate everything from that. i've still got to conditionally include the Eval and Compile functionality for DSL that have/don't have this capability. i've two remaining questions for this leg of the work. - Does anyone know how to reference maven dependencies within some flavor of maven-antrun-plugin? The original version does not appear to have this functionality and Sun's maven-antrun-extended-plugin (which is supposed to supply this functionality) has so little documentation (that i could find) that i couldn't get it to work after an hour our so. - This version requires that BNFC, as an executable, be available on the path. Is there a blessed way to handle this sort of dependency? - i've got a hare-brained scheme that will fix this -- a meta-compiler-compiler from BNFC's input format to ANTLR's. i could include such a transform as a part of the project or a dependency and test for the availability of BNFC and fall back to ANTLR if it's not available. If anybody wanted to give this round of updates a whirl, even give me a code review, i would be very grateful. Best wishes, --greg -- L.G. Meredith Managing Partner Biosimilarity LLC 1219 NW 83rd St Seattle, WA 98117 +1 206.650.3740 http://biosimilarity.blogspot.com --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to liftweb@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 -~--~~~~--~~--~--~---
[Lift] Re: rlambda lift project updated
On Thu, May 14, 2009 at 21:41, Meredith Gregory lgreg.mered...@gmail.comwrote:
Lifted,
i've added support to the rlambda lift
projecthttp://code.google.com/p/rlambda/taking it within range of being a
candidate DSL-archetype. At this point it
is possible simply to supply a .cf file in the src/main/bnfc directory and
it will generate everything from that. i've still got to conditionally
include the Eval and Compile functionality for DSL that have/don't have this
capability.
i've two remaining questions for this leg of the work.
- Does anyone know how to reference maven dependencies within some
flavor of maven-antrun-plugin? The original version does not appear to have
this functionality and Sun's maven-antrun-extended-plugin (which is
supposed
to supply this functionality) has so little documentation (that i could
find) that i couldn't get it to work after an hour our so.
If I understand your request :
${maven.runtime.classpath}
see
http://maven.apache.org/plugins/maven-antrun-plugin/examples/classpaths.html
-
- This version requires that BNFC, as an executable, be available on
the path. Is there a blessed way to handle this sort of dependency?
I don't know a simple solution.
-
- i've got a hare-brained scheme that will fix this -- a
meta-compiler-compiler from BNFC's input format to ANTLR's. i could
include
such a transform as a part of the project or a dependency and test for
the
availability of BNFC and fall back to ANTLR if it's not available.
If anybody wanted to give this round of updates a whirl, even give me a
code review, i would be very grateful.
Best wishes,
--greg
--
L.G. Meredith
Managing Partner
Biosimilarity LLC
1219 NW 83rd St
Seattle, WA 98117
+1 206.650.3740
http://biosimilarity.blogspot.com
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups
Lift group.
To post to this group, send email to liftweb@googlegroups.com
To unsubscribe from this group, send email to
liftweb+unsubscr...@googlegroups.com
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[Lift] Re: rlambda lift project updated
I've seen this demonstrated and the conceptual part is actually drop-dead simple. But maybe watching it work helps a lot. I might also add that watching Greg write some straightforward BNF to describe a complex relationship between objects in a simple DSL and then generate a Lift app from in -- all in about half an hour -- was so astonishing that I haven't been able to stop thinking about it and can barely wait to run into him again to ask questions about it. I'm not very bright, so Greg can correct me if I'm wrong here, but essentially you just write up your DSL in BNF, then you run the BNF compiler and out pops some Java classes (which you dump in your model directory). Then you extend those classes using Scala and you're good to go. Chas. Timothy Perrett wrote: Greg, I find this very interesting. How can I help you out here? I can certainly review your lift code, not so sure about some of the crazy conceptual stuff though! Cheers, Tim On May 14, 8:41 pm, Meredith Gregory lgreg.mered...@gmail.com wrote: Lifted, i've added support to the rlambda lift projecthttp://code.google.com/p/rlambda/taking it within range of being a candidate DSL-archetype. At this point it is possible simply to supply a .cf file in the src/main/bnfc directory and it will generate everything from that. i've still got to conditionally include the Eval and Compile functionality for DSL that have/don't have this capability. i've two remaining questions for this leg of the work. - Does anyone know how to reference maven dependencies within some flavor of maven-antrun-plugin? The original version does not appear to have this functionality and Sun's maven-antrun-extended-plugin (which is supposed to supply this functionality) has so little documentation (that i could find) that i couldn't get it to work after an hour our so. - This version requires that BNFC, as an executable, be available on the path. Is there a blessed way to handle this sort of dependency? - i've got a hare-brained scheme that will fix this -- a meta-compiler-compiler from BNFC's input format to ANTLR's. i could include such a transform as a part of the project or a dependency and test for the availability of BNFC and fall back to ANTLR if it's not available. If anybody wanted to give this round of updates a whirl, even give me a code review, i would be very grateful. Best wishes, --greg -- L.G. Meredith Managing Partner Biosimilarity LLC 1219 NW 83rd St Seattle, WA 98117 +1 206.650.3740 http://biosimilarity.blogspot.com --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to liftweb@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 -~--~~~~--~~--~--~---
[Lift] Re: rlambda lift project updated
Sounds good - we have a DSL that's used at work this could be really great for. Cheers, Tim On 15/05/2009 17:47, Charles F. Munat c...@munat.com wrote: I've seen this demonstrated and the conceptual part is actually drop-dead simple. But maybe watching it work helps a lot. I might also add that watching Greg write some straightforward BNF to describe a complex relationship between objects in a simple DSL and then generate a Lift app from in -- all in about half an hour -- was so astonishing that I haven't been able to stop thinking about it and can barely wait to run into him again to ask questions about it. I'm not very bright, so Greg can correct me if I'm wrong here, but essentially you just write up your DSL in BNF, then you run the BNF compiler and out pops some Java classes (which you dump in your model directory). Then you extend those classes using Scala and you're good to go. Chas. Timothy Perrett wrote: Greg, I find this very interesting. How can I help you out here? I can certainly review your lift code, not so sure about some of the crazy conceptual stuff though! Cheers, Tim On May 14, 8:41 pm, Meredith Gregory lgreg.mered...@gmail.com wrote: Lifted, i've added support to the rlambda lift projecthttp://code.google.com/p/rlambda/taking it within range of being a candidate DSL-archetype. At this point it is possible simply to supply a .cf file in the src/main/bnfc directory and it will generate everything from that. i've still got to conditionally include the Eval and Compile functionality for DSL that have/don't have this capability. i've two remaining questions for this leg of the work. - Does anyone know how to reference maven dependencies within some flavor of maven-antrun-plugin? The original version does not appear to have this functionality and Sun's maven-antrun-extended-plugin (which is supposed to supply this functionality) has so little documentation (that i could find) that i couldn't get it to work after an hour our so. - This version requires that BNFC, as an executable, be available on the path. Is there a blessed way to handle this sort of dependency? - i've got a hare-brained scheme that will fix this -- a meta-compiler-compiler from BNFC's input format to ANTLR's. i could include such a transform as a part of the project or a dependency and test for the availability of BNFC and fall back to ANTLR if it's not available. If anybody wanted to give this round of updates a whirl, even give me a code review, i would be very grateful. Best wishes, --greg -- L.G. Meredith Managing Partner Biosimilarity LLC 1219 NW 83rd St Seattle, WA 98117 +1 206.650.3740 http://biosimilarity.blogspot.com --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to liftweb@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 -~--~~~~--~~--~--~---
[Lift] Re: rlambda lift project updated
David,
Sweet! Thanks that little maven trick should eliminate one of my problems.
i've been thinking a bit more about the meta-compiler-compiler approach and
-- because i believe it gives me a way to generate Josh Suereth's LOLCode as
a side-effect -- i'm ever so inclined to take it. Who says side-effects are
bad?
Best wishes,
--greg
On Fri, May 15, 2009 at 7:38 AM, David Bernard
david.bernard...@gmail.comwrote:
On Thu, May 14, 2009 at 21:41, Meredith Gregory
lgreg.mered...@gmail.comwrote:
Lifted,
i've added support to the rlambda lift
projecthttp://code.google.com/p/rlambda/taking it within range of being a
candidate DSL-archetype. At this point it
is possible simply to supply a .cf file in the src/main/bnfc directory and
it will generate everything from that. i've still got to conditionally
include the Eval and Compile functionality for DSL that have/don't have this
capability.
i've two remaining questions for this leg of the work.
- Does anyone know how to reference maven dependencies within some
flavor of maven-antrun-plugin? The original version does not appear to
have
this functionality and Sun's maven-antrun-extended-plugin (which is
supposed
to supply this functionality) has so little documentation (that i could
find) that i couldn't get it to work after an hour our so.
If I understand your request :
${maven.runtime.classpath}
see
http://maven.apache.org/plugins/maven-antrun-plugin/examples/classpaths.html
-
- This version requires that BNFC, as an executable, be available on
the path. Is there a blessed way to handle this sort of dependency?
I don't know a simple solution.
-
- i've got a hare-brained scheme that will fix this -- a
meta-compiler-compiler from BNFC's input format to ANTLR's. i could
include
such a transform as a part of the project or a dependency and test for
the
availability of BNFC and fall back to ANTLR if it's not available.
If anybody wanted to give this round of updates a whirl, even give me a
code review, i would be very grateful.
Best wishes,
--greg
--
L.G. Meredith
Managing Partner
Biosimilarity LLC
1219 NW 83rd St
Seattle, WA 98117
+1 206.650.3740
http://biosimilarity.blogspot.com
--
L.G. Meredith
Managing Partner
Biosimilarity LLC
1219 NW 83rd St
Seattle, WA 98117
+1 206.650.3740
http://biosimilarity.blogspot.com
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups
Lift group.
To post to this group, send email to liftweb@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
-~--~~~~--~~--~--~---
[Lift] Re: rlambda lift project updated
Chas,
You're too kind. Fortunately, i can take none of the credit: language-based
design goes all the way back to Chomsky. ;-) For those who are not familiar
with this approach, a little cheat sheet goes a long way.
Classes ~ Types = Grammatical Categories
In English, the category associated with a symbol in a grammar is
essentially a type in a functional language, and for a good chunk of
OO-style classes, such a category also corresponds to a class. The main
trick is to recognize that this is not just for parsing, anymore. The
abstract syntax tree associated with such a grammar is essentially a family
of classes/types that addresses some domain model. This is really solid for
FP types, and for the POJO-style classes (which are essentially relations).
To illustrate, suppose we wanted to model some basic idea of reporting.
That is, we had
- a basic report structure -- that was a list of queries and their
responses
- an aggregate report structure -- that was merely a roll up of a bunch
of sub-reports
- a dependent report structure -- in which a report was a function of
some other reports
- an application report structure -- in which we apply dependent
reports to argument reports
One way to go about modeling this is as a little language of reports.
Report ::= BasicReport | AggregateReport | DependentReport |
ApplicationReport
BasicReport ::= ReportID { (Query,Response)* }
AggregateReport ::= [ Report* ]
DependentReport ::= ( Formal* ){ Report }
ApplicationReport ::= Report Report*
Formal ::= Variable
Query ::= ...
Response ::= ...
This is enough information to generate the entire class structure, with
persistence, plus a concrete language (with parser) that can be used for
testing (or other nefarious) purposes. To see an example of this -- the
little demo i gave Chas -- look herehttp://code.google.com/p/reportatrope/.
Note that this specifies only the *structural* aspects of the relationships
governing our model of reports. It doesn't give any sense of
- how to render reports, or even
- how to calculate the application of a dependent report to some
arguments
To this last point, those with a little more experience will spot that this
structure is remarkably similar to... (wait for it) the lambda calculus.
Yes, i've snuck in a little programming language structure to my model
because ... well... it turns out it's really necessary for most moderately
rich domains. This comes with a notion of evaluation that can, in principle,
provide a reasonable semantics for how one calculates application reports.
That gives some insight into why choose rlambda as the archetype. It also
indicates that adding some sort of rewrite rules to the grammar above might
be a good thing. In this case, the rewrite rule is something like
( f1, ..., fn ){ R } R1 ... Rn - R{ R1/f1, ..., Rn/fn }
In English, a dependent report with formal parameters f1, ..., fn, applied
to arguments R1, ..., Rn evaluates to the body of the dependent report with
the parameters replaced by the arguments. This indicates we have to add one
production to the grammar above
VariableReport ::= Variable
so that variables can actually occur in the body of reports!
There are a lot of technical details i'm eliding here. Further, it's not
like one is going to be able to autogenerate a production quality language
like Scala from a specification of this kind (yet!). But, it is a lot better
than beginning with a blank slate.
To the first bullet above, it turns out that there are some natural default
rendering's of structure so defined that -- in my view -- line up very well
with Charles' vision of the web app pipeline.
Best wishes,
--greg
On Fri, May 15, 2009 at 9:47 AM, Charles F. Munat c...@munat.com wrote:
I've seen this demonstrated and the conceptual part is actually
drop-dead simple. But maybe watching it work helps a lot.
I might also add that watching Greg write some straightforward BNF to
describe a complex relationship between objects in a simple DSL and then
generate a Lift app from in -- all in about half an hour -- was so
astonishing that I haven't been able to stop thinking about it and can
barely wait to run into him again to ask questions about it.
I'm not very bright, so Greg can correct me if I'm wrong here, but
essentially you just write up your DSL in BNF, then you run the BNF
compiler and out pops some Java classes (which you dump in your model
directory). Then you extend those classes using Scala and you're good to
go.
Chas.
Timothy Perrett wrote:
Greg, I find this very interesting.
How can I help you out here? I can certainly review your lift code,
not so sure about some of the crazy conceptual stuff though!
Cheers, Tim
On May 14, 8:41 pm, Meredith Gregory lgreg.mered...@gmail.com wrote:
Lifted,
i've added support to the rlambda lift
projecthttp://code.google.com/p/rlambda/taking it within range of
being a candidate DSL-archetype. At this point it
is
[Lift] Re: rlambda lift project updated
O. You've polished this up a bit. Very nice.
Chomsky? Isn't he that commie pinko America-hater?
Chas.
Meredith Gregory wrote:
Chas,
You're too kind. Fortunately, i can take none of the credit:
language-based design goes all the way back to Chomsky. ;-) For those
who are not familiar with this approach, a little cheat sheet goes a
long way.
Classes ~ Types = Grammatical Categories
In English, the category associated with a symbol in a grammar is
essentially a type in a functional language, and for a good chunk of
OO-style classes, such a category also corresponds to a class. The main
trick is to recognize that this is not just for parsing, anymore. The
abstract syntax tree associated with such a grammar is essentially a
family of classes/types that addresses some domain model. This is really
solid for FP types, and for the POJO-style classes (which are
essentially relations).
To illustrate, suppose we wanted to model some basic idea of reporting.
That is, we had
* a basic report structure -- that was a list of queries and their
responses
* an aggregate report structure -- that was merely a roll up of a
bunch of sub-reports
* a dependent report structure -- in which a report was a function
of some other reports
* an application report structure -- in which we apply dependent
reports to argument reports
One way to go about modeling this is as a little language of reports.
Report ::= BasicReport | AggregateReport | DependentReport |
ApplicationReport
BasicReport ::= ReportID { (Query,Response)* }
AggregateReport ::= [ Report* ]
DependentReport ::= ( Formal* ){ Report }
ApplicationReport ::= Report Report*
Formal ::= Variable
Query ::= ...
Response ::= ...
This is enough information to generate the entire class structure, with
persistence, plus a concrete language (with parser) that can be used for
testing (or other nefarious) purposes. To see an example of this -- the
little demo i gave Chas -- look here
http://code.google.com/p/reportatrope/. Note that this specifies only
the /structural/ aspects of the relationships governing our model of
reports. It doesn't give any sense of
* how to render reports, or even
* how to calculate the application of a dependent report to some
arguments
To this last point, those with a little more experience will spot that
this structure is remarkably similar to... (wait for it) the lambda
calculus. Yes, i've snuck in a little programming language structure to
my model because ... well... it turns out it's really necessary for most
moderately rich domains. This comes with a notion of evaluation that
can, in principle, provide a reasonable semantics for how one calculates
application reports. That gives some insight into why choose rlambda as
the archetype. It also indicates that adding some sort of rewrite rules
to the grammar above might be a good thing. In this case, the rewrite
rule is something like
( f1, ..., fn ){ R } R1 ... Rn - R{ R1/f1, ..., Rn/fn }
In English, a dependent report with formal parameters f1, ..., fn,
applied to arguments R1, ..., Rn evaluates to the body of the dependent
report with the parameters replaced by the arguments. This indicates we
have to add one production to the grammar above
VariableReport ::= Variable
so that variables can actually occur in the body of reports!
There are a lot of technical details i'm eliding here. Further, it's not
like one is going to be able to autogenerate a production quality
language like Scala from a specification of this kind (yet!). But, it is
a lot better than beginning with a blank slate.
To the first bullet above, it turns out that there are some natural
default rendering's of structure so defined that -- in my view -- line
up very well with Charles' vision of the web app pipeline.
Best wishes,
--greg
On Fri, May 15, 2009 at 9:47 AM, Charles F. Munat c...@munat.com
mailto:c...@munat.com wrote:
I've seen this demonstrated and the conceptual part is actually
drop-dead simple. But maybe watching it work helps a lot.
I might also add that watching Greg write some straightforward BNF to
describe a complex relationship between objects in a simple DSL and then
generate a Lift app from in -- all in about half an hour -- was so
astonishing that I haven't been able to stop thinking about it and can
barely wait to run into him again to ask questions about it.
I'm not very bright, so Greg can correct me if I'm wrong here, but
essentially you just write up your DSL in BNF, then you run the BNF
compiler and out pops some Java classes (which you dump in your model
directory). Then you extend those classes using Scala and you're
good to go.
Chas.
Timothy Perrett wrote:
Greg, I find this very interesting.
How can I help
[Lift] Re: rlambda lift project updated
Chas,
You know, with all his research on 'Manufacturing Consent', Noam might have
a 3rd career in managing open source projects. Since you've pinned the tail
on the donkey, so to speak, do you think there might be a connection between
ideology and design skills? i mean his work on grammars and computability
was really wicked clever. You don't think his pinko commie leanings could
like have any connection to his insights on linguistics and computation, do
you?
Best wishes,
--greg
On Fri, May 15, 2009 at 12:47 PM, Charles F. Munat c...@munat.com wrote:
O. You've polished this up a bit. Very nice.
Chomsky? Isn't he that commie pinko America-hater?
Chas.
Meredith Gregory wrote:
Chas,
You're too kind. Fortunately, i can take none of the credit:
language-based design goes all the way back to Chomsky. ;-) For those
who are not familiar with this approach, a little cheat sheet goes a
long way.
Classes ~ Types = Grammatical Categories
In English, the category associated with a symbol in a grammar is
essentially a type in a functional language, and for a good chunk of
OO-style classes, such a category also corresponds to a class. The main
trick is to recognize that this is not just for parsing, anymore. The
abstract syntax tree associated with such a grammar is essentially a
family of classes/types that addresses some domain model. This is really
solid for FP types, and for the POJO-style classes (which are
essentially relations).
To illustrate, suppose we wanted to model some basic idea of reporting.
That is, we had
* a basic report structure -- that was a list of queries and their
responses
* an aggregate report structure -- that was merely a roll up of a
bunch of sub-reports
* a dependent report structure -- in which a report was a function
of some other reports
* an application report structure -- in which we apply dependent
reports to argument reports
One way to go about modeling this is as a little language of reports.
Report ::= BasicReport | AggregateReport | DependentReport |
ApplicationReport
BasicReport ::= ReportID { (Query,Response)* }
AggregateReport ::= [ Report* ]
DependentReport ::= ( Formal* ){ Report }
ApplicationReport ::= Report Report*
Formal ::= Variable
Query ::= ...
Response ::= ...
This is enough information to generate the entire class structure, with
persistence, plus a concrete language (with parser) that can be used for
testing (or other nefarious) purposes. To see an example of this -- the
little demo i gave Chas -- look here
http://code.google.com/p/reportatrope/. Note that this specifies only
the /structural/ aspects of the relationships governing our model of
reports. It doesn't give any sense of
* how to render reports, or even
* how to calculate the application of a dependent report to some
arguments
To this last point, those with a little more experience will spot that
this structure is remarkably similar to... (wait for it) the lambda
calculus. Yes, i've snuck in a little programming language structure to
my model because ... well... it turns out it's really necessary for most
moderately rich domains. This comes with a notion of evaluation that
can, in principle, provide a reasonable semantics for how one calculates
application reports. That gives some insight into why choose rlambda as
the archetype. It also indicates that adding some sort of rewrite rules
to the grammar above might be a good thing. In this case, the rewrite
rule is something like
( f1, ..., fn ){ R } R1 ... Rn - R{ R1/f1, ..., Rn/fn }
In English, a dependent report with formal parameters f1, ..., fn,
applied to arguments R1, ..., Rn evaluates to the body of the dependent
report with the parameters replaced by the arguments. This indicates we
have to add one production to the grammar above
VariableReport ::= Variable
so that variables can actually occur in the body of reports!
There are a lot of technical details i'm eliding here. Further, it's not
like one is going to be able to autogenerate a production quality
language like Scala from a specification of this kind (yet!). But, it is
a lot better than beginning with a blank slate.
To the first bullet above, it turns out that there are some natural
default rendering's of structure so defined that -- in my view -- line
up very well with Charles' vision of the web app pipeline.
Best wishes,
--greg
On Fri, May 15, 2009 at 9:47 AM, Charles F. Munat c...@munat.com
mailto:c...@munat.com wrote:
I've seen this demonstrated and the conceptual part is actually
drop-dead simple. But maybe watching it work helps a lot.
I might also add that watching Greg write some straightforward BNF to
describe a complex relationship between objects in a simple DSL and
then
generate a Lift app from in
