Suppose the grammar is given, how to design the code generation process?
start(res) ::= template. { **how to write stuff here?? Is it true there will only be
one correct way to write this? And Let's suppose the programming language is also given** }
This is a pretty broad question, with many books an articles written on it. The general heading you're looking for is Syntax directed translation, and the classic reference is the Dragon Book
Related
Are there any support for first-class patterns in Erlang?
f(SomeMagicPattern) ->
receive
SomeMagicPattern -> ok
end.
If the answer is no (support), do you know any other approach for achieving this? For example, using macros?
No, Erlang doesn't have first-class patterns out of the box.
There are two ways of implementing this:
Macros. Widely used, for example in testing tools like EUnit and PropEr. Say, EUnit has an ?assertMatch macro, which is in fact an example of first-class patterns:
?assertMatch({ok, _}, Result)
Parse transforms. Harder to write, but potentially more powerful, since using them you can access Erlang abstract code and rewrite it completely, in any way you desire. There's a nice link to a series of tutorials on parse transforms here: Is there a good, complete tutorial on Erlang parse transforms available?
As demeshchuk points out this is not the case.
There is however a proposal to add something similar to the language:
http://www.erlang.org/eeps/eep-0029.html
Whether or not this is a good idea is a completely different question...
I just read the document of eclipse xtext, and found the language it uses is similar to java, but with a few differences:
http://www.eclipse.org/Xtext/documentation/2_0_0/040-first-code-generator.php
For example, it has such a code snippet:
def compile(Entity e) '''
package «e.eContainer.fullyQualifiedName»;
public class «e.name» {
}
'''
What's the language?
The language you are referring to is called Xtend2 and is a Java-like programming language that has been tailored for code generation. It features some very useful concepts such as closures, dynamic dispatch, type inference and the rich strings you've already seen. Xtend2 code can be executed by the JVM since it's been translated to human-readable Java code each time you hit save. Sven Efftinge blogged about Xtend2's core ideas a while ago. There's a tutorial on the Xtext website (the page you mentioned in your question), too.
Also, Xtend2 shares most ideas of Xbase, a reusable foundation for programming languages built with Xtext.
It appears to be some sort of a notation for code generation (which of course one could surmise by reading the page title). And another "duhh!": They appear to call the overall package Xtext. However, I've not found anything that names the 2-3 different languages they use for grammar, semantics, etc.
Looks like Scala + some template with so called merge codes.
http://www.scala-lang.org/
Does anyone know of any examples of code written in prolog to implement a DSL to generate perl code?
DCGs might be an excellent choice!
I have used a similar approach for generation of UML class diagrams (really, graphviz code for such diagrams) from simple English sentences (shameless-plug: paper here). It should be possible to do something similar with generation of Perl code instead.
In the paper above, we use a constraint store (CHR) as intermediate representation which allows some extra reasoning power. Alternatively you can build a representation as an output feature/argument of the DCG.
Note that DCGs can be useful both for the parsing of your sentences and the generation of your Perl code.
Well, not exactly what you are asking for, but maybe you can use AI::Prolog for what you are looking for. That way you may be able to use Perl and generate the Perl code you want.
I'm not sure why you would want to do that?
Perl is a very expressive language, I'm not sure why you'd want to try to generate Perl code from Prolog; in order to make it useful, you'd be getting closer and closer to Perl in your "DSL", by which point you'd be better off just writing some Perl, surely?
I think you need to expand this question a bit to cover what you're trying to achieve in a little more detail.
SWI-Prolog library(http/html_write) library builds on DCG a DSL for page layout.
It shows a well tought model for integrating Prolog and HTML, but doesn't attempt to cover the entire problem. The 'residual logic' on the client side remains underspecified, but this is reasonable, being oriented on practical issues 'reporting' from RDF.
Thus the 'small detail' client interaction logic is handled in a 'black box' fashion, and such demanded to YUI components in the published application (the award winner Cliopatria).
The library it's extensible, but being very detailed, I guess for your task you should eventually reuse just the ideas behind.
I realize that it is impossible to have one language that is best for everything.
But there is a class of simple programs, whose source code looks virtually identical in any language.
I am thinking not just "hello world", but also arithmetics, maybe string manipulation, basic stuff that you would typically see in utility classes.
I would like to keep my utilities in this meta-language and have it automatically translated to a bunch of popular languages. I do this by hand right now.
Again, I do not ask for translation of every single possible program. I am thinking a very limited, simple language, but superportable.
Do you know of anything like that? Is there a reason why it should not exist?
Check Haxe, and its Wikipedia page. It's open source and its main purpose is what you describe: generating code in many languages from only one source.
Just about any language that you choose is going to have some feature that doesn't map to another in a natural way. The closest thing I can think of is probably a useful subset of JavaScript. Of course, if you are the language author you can limit it as much as you want, providing only constructs that are common to just about any language (loops, conditionals, etc.)
For purposes of mutability, an XML representation would be best, but you wouldn't want to code in it.
If you find that there is no universal language, you can try a pragmatic model-driven development approach, using a template-based code generator.
On the template you keep the underlying concepts of an algorithm. Then, you would add code for this algorithm in one or more specific languages (C++,Java,JS,Python) when necessary. You would have to do it anyway, whatever the language or approach you choose. A configuration switch would pick the correct language for any template you apply.
AtomWeaver is a code generator that works with templates and employs ABSE as the modeling approach.
I did some looking and found this.
https://www.indiegogo.com/projects/universal-programming-language
looks interesting
A classic Pascal is very simple. Oberon is another similar option. Or you could invent your own derivative language similar to the pseudocode from the computer science textbooks. It's trivial to implement a translator from one of that languages into any decent modern imperative language.
I'm curious if anyone understands, knows or can point me to comprehensive literature or source code on how Google created their popular passage blocks feature. However, if you know of any other application that can do the same please post your answer too.
If you do not know what I am writing about here is a link to an example of Popular Passages. When you look at the overview of the book Modelling the legal decision process for information technology applications ... By Georgios N. Yannopoulos you can see something like:
Popular passages
... direction, indeterminate. We have
not settled, because we have not
anticipated, the question which will
be raised by the unenvisaged case when
it occurs; whether some degree of
peace in the park is to be sacrificed
to, or defended against, those
children whose pleasure or interest it
is to use these things. When the
unenvisaged case does arise, we
confront the issues at stake and can
then settle the question by choosing
between the competing interests in the
way which best satisfies us. In
doing... Page 86
Appears in 15 books from 1968-2003
This would be a world fit for
"mechanical" jurisprudence. Plainly
this world is not our world; human
legislators can have no such knowledge
of all the possible combinations of
circumstances which the future may
bring. This inability to anticipate
brings with it a relative
indeterminacy of aim. When we are bold
enough to frame some general rule of
conduct (eg, a rule that no vehicle
may be taken into the park), the
language used in this context fixes
necessary conditions which anything
must satisfy... Page 86
Appears in 8 books from 1968-2000
more
It must be an intensive pattern matching process. I can only think of n-gram models, text corpus, automatic plagisrism detection. But, sometimes n-grams are probabilistic models for predicting the next item in a sequence and text corpus (to my knowledge) are manually created. And, in this particular case, popular passages, there can be a great deal of words.
I am really lost. If I wanted to create such a feature, how or where should I start? Also, include in your response what programming languages are best suited for this stuff: F# or any other functional lang, PERL, Python, Java... (I am becoming a F# fan myself)
PS: can someone include the tag automatic-plagiarism-detection, because i can't
Read this ACM paper by Kolak and Schilit, the Google researchers who developed Popular Passages. There are also a few relevant slides from this MapReduce course taught by Baldridge and Lease at The University of Texas at Austin.
In the small sample I looked over, it looks like all the passages picked were inline or block quotes. Just a guess, but perhaps Google Books looks for quote marks/differences in formatting and a citation, then uses a parsed version of the bibliography to associate the quote with the source. Hooray for style manuals.
This approach is obviously of no help to detect plagiarism, and is of little help if the corpus isn't in a format that preserves text formatting.
If you know which books are citing or referencing other books you don't need to look at all possible books only the books that are citing each other. If is is scientific reference often line and page numbers are included with the quote or can be found in the bibliography at the end of the book, so maybe google parses only this informations?
Google scholar certainly has the information about citing from paper to paper maybe from book to book too.