Maybe it's a basic question, but what differences are there between:
- a web project developped with ES3 support and
- a web project developped with ES5 support?
In other words, what enhancements can you add to your projects if you support ES5 ?
It's probably hard to list here all things that are new in ES5, but the ones that may be helpful in your case are mostly related to language improvements. Some of the key points:
Methods for searching and manipulating array contents: indexOf, map, filter, reduce, forEach, etc.
Standard of representation for dates as strings (ISO 8601).
Functions for converting objects to and from JSON
'use strict' - strict mode changes some JavaScript silent errors to throw errors, fixes some Javascript mistakes to enable better optimisation and so on.
Switching to ES5 can probably speed up your development process a bit and can help make your code robust and optimised.
Related
Is there any type of list of what features the babel-polyfill supports? We just started using babel and i'm wondering if some of the dependencies we currently rely on can be eliminated like es6-promises & whatwg-fetch. If babel-polyfill supported promises of course there would be no need to include es6-promises.
I think after some research i figured it out. Babel-Polyfill is pretty much core.js + Regenerator Runtime . Look at those projects individually to see what features will be polyfilled. For example, at the time of this writing core.js:
Fetch:
window.fetch is not a cross-platform feature, in some environments it
makes no sense. For this reason, I don't think it should be in
core-js. Looking at a large number of requests it may be added in the
future. Now you can use, for example, this polyfill.
Promises:
Modular standard library for JavaScript. Includes polyfills for
ECMAScript 5, ECMAScript 6: promises, symbols, collections, iterators,
typed arrays, ECMAScript 7+ proposals, setImmediate, etc.
So i need whatwg-fetch but i don't need es6-promises. Tested in IE11 (which doesn't have promises) so it appears to be working.
I am using Eclipse (version: Kepler Service Release 1) with Prolog Development Tool (PDT) plug-in for Prolog development in Eclipse. Used these installation instructions: http://sewiki.iai.uni-bonn.de/research/pdt/docs/v0.x/download.
I am working with Multi-Agent IndiGolog (MIndiGolog) 0 (the preliminary prolog version of MIndiGolog). Downloaded from here: http://www.rfk.id.au/ramblings/research/thesis/. I want to use MIndiGolog because it represents time and duration of actions very nicely (I want to do temporal planning), and it supports planning for multiple agents (including concurrency).
MIndiGolog is a high-level programming language based on situation calculus. Everything in the language is exactly according to situation calculus. This however does not fit with the project I'm working on.
This other high-level programming language, Incremental Deterministic (Con)Golog (IndiGolog) (Download from here: http://sourceforge.net/p/indigolog/code/ci/master/tree/) (also made with Prolog), is also (loosly) based on situation calculus, but uses fluents in a very different way. It makes use of causes_val-predicates to denote which action changes which fluent in what way, and it does not include the situation in the fluent!
However, this is what the rest of the team actually wants. I need to rewrite MIndiGolog so that it is still an offline planner, with the nice representation of time and duration of actions, but with the causes_val predicate of IndiGolog to change the values of the fluents.
I find this extremely hard to do, as my knowledge in Prolog and of situation calculus only covers the basics, but they see me as the expert. I feel like I'm in over my head and could use all the help and/or advice I can get.
I already removed the situations from my fluents, made a planning domain with causes_val predicates, and tried to add IndiGolog code into MIndiGolog. But with no luck. Running the planner just returns "false." And I can make little sense of the trace, even when I use the GUI-tracer version of the SWI-Prolog debugger or when I try to place spy points as strategically as possible.
Thanks in advance,
Best, PJ
If you are still interested (sounds like you might not be): this isn't actually very hard.
If you look at Reiter's book, you will find that causes_vals are just effect axioms, while the fluents that mention the situation are usually successor-state-axioms. There is a deterministic way to convert from the former to the latter, and the correct interpretation of the causes_vals is done in the implementation of regression. This is always the same, and you can just copy that part of Prolog code from indiGolog to your flavor.
Does anyone here try to adopt xtext2 and migrate from xtext1.x to xtext2.0?
It seems xtext2 brings many new atractive features. Such as A Reusable Expression Language and Xtend: A Code Generation Language . Many performance enhancement is made to the Xtext workbench and rename capability. So any one tell you experence about xtext2? Probably this is a bit early question. But I just wait and see.
xtext2 homepage
I updated an existing, not too complex language from Xtext 1 to Xtext 2, and tried to develop a new one using Xtext2 and XBase. I had to re-run the code generation step, and also had to modify the hand-written validators, because the error and warnings locations are to be specified using literals instead of integers. E.g.
error("File does not exist with path: " + path, fileReference, ViatraTestDslPackage.FILE__PATH);
is to be replaced with
error("File does not exist with path: " + path, ViatraTestDslPackage.Literals.FILE__PATH);
Similarly, the workflow has to be changed as well to incorporate some new features: the outline API uses different fragments (outline.OutlineTreeProviderFragment and outline.QuickOutlineFragment), for rename and compare support new fragments are to be added (refactoring.RefactorElementNameFragment and compare.CompareFragment).
With my experiments of XBase it seems, that adding that to a language that already supported some kind of expressions can be labour-intensive, because either old expressions has to be replaced with XBase expressions (or at least altered in a way to make them available in XBase expressions), otherwise you have to maintain two kind of expression support in your code generator or interpreter.
To conclude my answer, I believe, if you have a simple Xtext 1.0 editor, where you mostly relied on the automatically generated features, migrating to Xtext 2.0 seems easy and recommended; however, if you customized a lot of things in manually written code, be careful, because the migration might not be straight-forward, and I have found no real migration guide.
http://www.eclipse.org/Xtext/documentation/2_0_0/213-migrating-from-1.0.php#migrating_from_1_0_x_5_4
I just find this useful link.
Also I do meet some problem especially in serialization module. Luckily in mwe2 file, it leaves a version 1.0 serialization, i use that and fix the problem when using version 2.0 serialization module. Not knowing why..
Another problem is there is a strange bug in the xtext validation. It always complain about ClassCastException. cast from String to QualifiedName error.
It is still early considering the recent release date:
The team have just presented/demo'ed XTend2 in democamps during last month (June 2011).
My scala application needs to perform simple operations over large arrays of integers & doubles, and performance is a bottleneck. I've struggled to put my finger on exactly when certain optimizations kick in (e.g. escape analysis) although I can observe their results through various benchmarking. I'd love to do some AOT compilation of my scala application, so I can see or enforce (or implement) certain optimizations ... or compile to native code, if possible, so I can cut corners like bounds checking and observe if it makes a difference.
My question: what alternative compilation methods work for scala? I'm interested in tools like llvm, vmkit, soot, gcj, etc. Who is using those successfully with scala at this point, or are none of these methods currently compatible or maintained?
GCJ can compile JVM classes to native code. This blog describes tests done with Scala code: http://lampblogs.epfl.ch/b2evolution/blogs/index.php/2006/10/02/scala_goes_native_almost?blog=7
To answer my own question, there is no alternative backend for Scala except for the JVM. The .NET backend has been in development for a long time, but its status is unclear. The LLVM backend is also not yet ready for use, and it's not clear what its future is.
I am doing a compilers discipline at college and we must generate code for our invented language to any platform we want to. I think the simplest case is generating code for the Java JVM or .NET CLR. Any suggestion which one to choose, and which APIs out there can help me on this task? I already have all the semantic analysis done, just need to generate code for a given program.
Thank you
From what I know, on higher level, two VMs are actually quite similar: both are classic stack-based machines, with largely high-level operations (e.g. virtual method dispatch is an opcode). That said, CLR lets you get down to the metal if you want, as it has raw data pointers with arithmetic, raw function pointers, unions etc. It also has proper tailcalls. So, if the implementation of language needs any of the above (e.g. Scheme spec mandates tailcalls), or if it is significantly advantaged by having those features, then you would probably want to go the CLR way.
The other advantage there is that you get a stock API to emit bytecode there - System.Reflection.Emit - even though it is somewhat limited for full-fledged compiler scenarios, it is still generally enough for a simple compiler.
With JVM, two main advantages you get are better portability, and the fact that bytecode itself is arguably simpler (because of less features).
Another option that i came across what a library called run sharp that can generate the MSIL code in runtime using emit. But in a nicer more user friendly way that is more like c#. The latest version of the library can be found here.
http://code.google.com/p/runsharp/
In .NET you can use the Reflection.Emit Namespace to generate MSIL code.
See the msdn link: http://msdn.microsoft.com/en-us/library/3y322t50.aspx