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I'm just wondering what "implementation-agnostic" means? I didn't find any explanation. I mean it in this context: "an implementation-agnostic engineering approach".
The opposite of "implementation-agnostic" is "implementation-specific".
Some examples should make the difference clear:
Implementation-agnostic
Synonym: Implementation-independent
Examples:
Sorting algorithm "Quicksort"
Algorithms written in Pseudo-Code
The examples above can be implemented with every programming language
(Assembler, BASIC, C#, C++, Java, JavaScript, ...)
Implementation-specific
Synonym: Implementation-dependent
Examples:
Device drivers,
Machine language code for AMD (tm) or Intel (tm) Processors
The examples above run only on the hardware they are written for.
But also software that depends on or is using other software, dependency injection, interfaces, operating systems, services or frameworks is implementation-specific (for example, although .NETs intermediate language MSIL can run on different hardware or operating systems, it still depends on the .NET framework and hence is implementation-specific).
This is often used to discuss a problem without committing to a particular implementation. Doing so may lead to choosing an implementation / tool that's best suited for the problem rather than having to worry about the limitations of an already chosen solution during the problem definition.
Agnostic, in this context, means "doesn't care about". So implementation agnostic is something that does not care about the implementation.
To say that a solution is implementation-agnostic is to say that it's not reliant on specific technologies, programming languages etc. Pseudocode would be a good example of an implementation-agnostic tool, as would UML for modelling.
I'm making the transition from Java to PHP/Javascript and discovering all the practical aspects of using a weakly typed language.
As I'm in a position to fully compare the two I'd like to know the pros and cons of each approach. Also, are there any other forms of typing out there?
A weakly dynamically typed programming language (like PHP) made that the programmer's mistakes occur as non-coherent behaviours (for instance, the program gonna display stupid informations).
With a strongly dynamically typed language (like python), the programming mistakes causes error message. It makes the mistakes easier to uncover and diagnosis but in general the program became not usable after the message has been shown.
Finally, with a strongly statically typed language (like Java, Ada, OCaml, Haskell, ...) some mistakes can be uncovered at compile time and hence reduce the risk to provide an bugged program. (but the release occurs later)
Yes. Python uses Dynamic Typing.
Generally it's a matter of personal preference and the role that the architects of a given language's intended use.
PHP (a scripting language) for example makes sense to be weakly typed, as the tasks it generally performs are far less complex, and require less constraints then say a compiled language.
Regarding your final question, Mathematica is said to be "typeless."
High-level, typeless, dynamic language with consistent symbolic syntax and semantics across all data, functions, and interfaces
PHP/javascript can be used to develope better looking UI's than Java. PHP will be having less constraints and easy to learn and execute than java.
This question already has answers here:
What is the difference between a framework and a library? [closed]
(22 answers)
Closed 6 years ago.
What is the difference between a Framework, a Toolkit and a Library?
The most important difference, and in fact the defining difference between a library and a framework is Inversion of Control.
What does this mean? Well, it means that when you call a library, you are in control. But with a framework, the control is inverted: the framework calls you. (This is called the Hollywood Principle: Don't call Us, We'll call You.) This is pretty much the definition of a framework. If it doesn't have Inversion of Control, it's not a framework. (I'm looking at you, .NET!)
Basically, all the control flow is already in the framework, and there's just a bunch of predefined white spots that you can fill out with your code.
A library on the other hand is a collection of functionality that you can call.
I don't know if the term toolkit is really well defined. Just the word "kit" seems to suggest some kind of modularity, i.e. a set of independent libraries that you can pick and choose from. What, then, makes a toolkit different from just a bunch of independent libraries? Integration: if you just have a bunch of independent libraries, there is no guarantee that they will work well together, whereas the libraries in a toolkit have been designed to work well together – you just don't have to use all of them.
But that's really just my interpretation of the term. Unlike library and framework, which are well-defined, I don't think that there is a widely accepted definition of toolkit.
Martin Fowler discusses the difference between a library and a framework in his article on Inversion of Control:
Inversion of Control is a key part of
what makes a framework different to a
library. A library is essentially a
set of functions that you can call,
these days usually organized into
classes. Each call does some work and
returns control to the client.
A framework embodies some abstract
design, with more behavior built in.
In order to use it you need to insert
your behavior into various places in
the framework either by subclassing or
by plugging in your own classes. The
framework's code then calls your code
at these points.
To summarize: your code calls a library but a framework calls your code.
Diagram
If you are a more visual learner, here is a diagram that makes it clearer:
(Credits: http://tom.lokhorst.eu/2010/09/why-libraries-are-better-than-frameworks)
The answer provided by Barrass is probably the most complete. However, the explanation could easily be stated more clearly. Most people miss the fact that these are all nested concepts. So let me lay it out for you.
When writing code:
eventually you discover sections of code that you're repeating in your program, so you refactor those into Functions/Methods.
eventually, after having written a few programs, you find yourself copying functions you already made into new programs. To save yourself time you bundle those functions into Libraries.
eventually you find yourself creating the same kind of user interfaces every time you make use of certain libraries. So you refactor your work and create a Toolkit that allows you to create your UIs more easily from generic method calls.
eventually, you've written so many apps that use the same toolkits and libraries that you create a Framework that has a generic version of this boilerplate code already provided so all you need to do is design the look of the UI and handle the events that result from user interaction.
Generally speaking, this completely explains the differences between the terms.
Introduction
There are various terms relating to collections of related code, which have both historical (pre-1994/5 for the purposes of this answer) and current implications, and the reader should be aware of both, particularly when reading classic texts on computing/programming from the historic era.
Library
Both historically, and currently, a library is a collection of code relating to a specific task, or set of closely related tasks which operate at roughly the same level of abstraction. It generally lacks any purpose or intent of its own, and is intended to be used by (consumed) and integrated with client code to assist client code in executing its tasks.
Toolkit
Historically, a toolkit is a more focused library, with a defined and specific purpose. Currently, this term has fallen out of favour, and is used almost exclusively (to this author's knowledge) for graphical widgets, and GUI components in the current era. A toolkit will most often operate at a higher layer of abstraction than a library, and will often consume and use libraries itself. Unlike libraries, toolkit code will often be used to execute the task of the client code, such as building a window, resizing a window, etc. The lower levels of abstraction within a toolkit are either fixed, or can themselves be operated on by client code in a proscribed manner. (Think Window style, which can either be fixed, or which could be altered in advance by client code.)
Framework
Historically, a framework was a suite of inter-related libraries and modules which were separated into either 'General' or 'Specific' categories. General frameworks were intended to offer a comprehensive and integrated platform for building applications by offering general functionality, such as cross platform memory management, multi-threading abstractions, dynamic structures (and generic structures in general). Historical general frameworks (Without dependency injection, see below) have almost universally been superseded by polymorphic templated (parameterised) packaged language offerings in OO languages, such as the STL for C++, or in packaged libraries for non-OO languages (guaranteed Solaris C headers). General frameworks operated at differing layers of abstraction, but universally low level, and like libraries relied on the client code carrying out it's specific tasks with their assistance.
'Specific' frameworks were historically developed for single (but often sprawling) tasks, such as "Command and Control" systems for industrial systems, and early networking stacks, and operated at a high level of abstraction and like toolkits were used to carry out execution of the client codes tasks.
Currently, the definition of a framework has become more focused and taken on the "Inversion of Control" principle as mentioned elsewhere as a guiding principle, so program flow, as well as execution is carried out by the framework. Frameworks are still however targeted either towards a specific output; an application for a specific OS for example (MFC for MS Windows for example), or for more general purpose work (Spring framework for example).
SDK: "Software Development Kit"
An SDK is a collection of tools to assist the programmer to create and deploy code/content which is very specifically targeted to either run on a very particular platform or in a very particular manner. An SDK can consist of simply a set of libraries which must be used in a specific way only by the client code and which can be compiled as normal, up to a set of binary tools which create or adapt binary assets to produce its (the SDK's) output.
Engine
An Engine (In code collection terms) is a binary which will run bespoke content or process input data in some way. Game and Graphics engines are perhaps the most prevalent users of this term, and are almost universally used with an SDK to target the engine itself, such as the UDK (Unreal Development Kit) but other engines also exist, such as Search engines and RDBMS engines.
An engine will often, but not always, allow only a few of its internals to be accessible to its clients. Most often to either target a different architecture, change the presentation of the output of the engine, or for tuning purposes. Open Source Engines are by definition open to clients to change and alter as required, and some propriety engines are fixed completely. The most often used engines in the world however, are almost certainly JavaScript Engines. Embedded into every browser everywhere, there are a whole host of JavaScript engines which will take JavaScript as an input, process it, and then output to render.
API: "Application Programming Interface"
The final term I am answering is a personal bugbear of mine: API, was historically used to describe the external interface of an application or environment which, itself was capable of running independently, or at least of carrying out its tasks without any necessary client intervention after initial execution. Applications such as Databases, Word Processors and Windows systems would expose a fixed set of internal hooks or objects to the external interface which a client could then call/modify/use, etc to carry out capabilities which the original application could carry out. API's varied between how much functionality was available through the API, and also, how much of the core application was (re)used by the client code. (For example, a word processing API may require the full application to be background loaded when each instance of the client code runs, or perhaps just one of its linked libraries; whereas a running windowing system would create internal objects to be managed by itself and pass back handles to the client code to be utilised instead.
Currently, the term API has a much broader range, and is often used to describe almost every other term within this answer. Indeed, the most common definition applied to this term is that an API offers up a contracted external interface to another piece of software (Client code to the API). In practice this means that an API is language dependent, and has a concrete implementation which is provided by one of the above code collections, such as a library, toolkit, or framework.
To look at a specific area, protocols, for example, an API is different to a protocol which is a more generic term representing a set of rules, however an individual implementation of a specific protocol/protocol suite that exposes an external interface to other software would most often be called an API.
Remark
As noted above, historic and current definitions of the above terms have shifted, and this can be seen to be down to advances in scientific understanding of the underlying computing principles and paradigms, and also down to the emergence of particular patterns of software. In particular, the GUI and Windowing systems of the early nineties helped to define many of these terms, but since the effective hybridisation of OS Kernel and Windowing system for mass consumer operating systems (bar perhaps Linux), and the mass adoption of dependency injection/inversion of control as a mechanism to consume libraries and frameworks, these terms have had to change their respective meanings.
P.S. (A year later)
After thinking carefully about this subject for over a year I reject the IoC principle as the defining difference between a framework and a library. There ARE a large number of popular authors who say that it is, but there are an almost equal number of people who say that it isn't. There are simply too many 'Frameworks' out there which DO NOT use IoC to say that it is the defining principle. A search for embedded or micro controller frameworks reveals a whole plethora which do NOT use IoC and I now believe that the .NET language and CLR is an acceptable descendant of the "general" framework. To say that IoC is the defining characteristic is simply too rigid for me to accept I'm afraid, and rejects out of hand anything putting itself forward as a framework which matches the historical representation as mentioned above.
For details of non-IoC frameworks, see, as mentioned above, many embedded and micro frameworks, as well as any historical framework in a language that does not provide callback through the language (OK. Callbacks can be hacked for any device with a modern register system, but not by the average programmer), and obviously, the .NET framework.
A library is simply a collection of methods/functions wrapped up into a package that can be imported into a code project and re-used.
A framework is a robust library or collection of libraries that provides a "foundation" for your code. A framework follows the Inversion of Control pattern. For example, the .NET framework is a large collection of cohesive libraries in which you build your application on top of. You can argue there isn't a big difference between a framework and a library, but when people say "framework" it typically implies a larger, more robust suite of libraries which will play an integral part of an application.
I think of a toolkit the same way I think of an SDK. It comes with documentation, examples, libraries, wrappers, etc. Again, you can say this is the same as a framework and you would probably be right to do so.
They can almost all be used interchangeably.
very, very similar, a framework is usually a bit more developed and complete then a library, and a toolkit can simply be a collection of similar librarys and frameworks.
a really good question that is maybe even the slightest bit subjective in nature, but I believe that is about the best answer I could give.
Library
I think it's unanimous that a library is code already coded that you can use so as not to have to code it again. The code must be organized in a way that allows you to look up the functionality you want and use it from your own code.
Most programming languages come with standard libraries, especially some code that implements some kind of collection. This is always for the convenience that you don't have to code these things yourself. Similarly, most programming languages have construct to allow you to look up functionality from libraries, with things like dynamic linking, namespaces, etc.
So code that finds itself often needed to be re-used is great code to be put inside a library.
Toolkit
A set of tools used for a particular purpose. This is unanimous. The question is, what is considered a tool and what isn't. I'd say there's no fixed definition, it depends on the context of the thing calling itself a toolkit. Example of tools could be libraries, widgets, scripts, programs, editors, documentation, servers, debuggers, etc.
Another thing to note is the "particular purpose". This is always true, but the scope of the purpose can easily change based on who made the toolkit. So it can easily be a programmer's toolkit, or it can be a string parsing toolkit. One is so broad, it could have tool touching everything programming related, while the other is more precise.
SDKs are generally toolkits, in that they try and bundle a set of tools (often of multiple kind) into a single package.
I think the common thread is that a tool does something for you, either completely, or it helps you do it. And a toolkit is simply a set of tools which all perform or help you perform a particular set of activities.
Framework
Frameworks aren't quite as unanimously defined. It seems to be a bit of a blanket term for anything that can frame your code. Which would mean: any structure that underlies or supports your code.
This implies that you build your code against a framework, whereas you build a library against your code.
But, it seems that sometimes the word framework is used in the same sense as toolkit or even library. The .Net Framework is mostly a toolkit, because it's composed of the FCL which is a library, and the CLR, which is a virtual machine. So you would consider it a toolkit to C# development on Windows. Mono being a toolkit for C# development on Linux. Yet they called it a framework. It makes sense to think of it this way too, since it kinds of frame your code, but a frame should more support and hold things together, then do any kind of work, so my opinion is this is not the way you should use the word.
And I think the industry is trying to move into having framework mean an already written program with missing pieces that you must provide or customize. Which I think is a good thing, since toolkit and library are great precise terms for other usages of "framework".
Framework: installed on you machine and allowing you to interact with it. without the framework you can't send programming commands to your machine
Library: aims to solve a certain problem (or several problems related to the same category)
Toolkit: a collection of many pieces of code that can solve multiple problems on multiple issues (just like a toolbox)
It's a little bit subjective I think. The toolkit is the easiest. It's just a bunch of methods, classes that can be use.
The library vs the framework question I make difference by the way to use them. I read somewhere the perfect answer a long time ago. The framework calls your code, but on the other hand your code calls the library.
In relation with the correct answer from Mittag:
a simple example. Let's say you implement the ISerializable interface (.Net) in one of your classes. You make use of the framework qualities of .Net then, rather than it's library qualities. You fill in the "white spots" (as mittag said) and you have the skeleton completed. You must know in advance how the framework is going to "react" with your code. Actually .net IS a framework, and here is where i disagree with the view of Mittag.
The full, complete answer to your question is given very lucidly in Chapter 19 (the whole chapter devoted to just this theme) of this book, which is a very good book by the way (not at all "just for Smalltalk").
Others have noted that .net may be both a framework and a library and a toolkit depending on which part you use but perhaps an example helps. Entity Framework for dealing with databases is a part of .net that does use the inversion of control pattern. You let it know your models it figures out what to do with them. As a programmer it requires you to understand "the mind of the framework", or more realistically the mind of the designer and what they are going to do with your inputs. datareader and related calls, on the other hand, are simply a tool to go get or put data to and from table/view and make it available to you. It would never understand how to take a parent child relationship and translate it from object to relational, you'd use multiple tools to do that. But you would have much more control on how that data was stored, when, transactions, etc.
I'm currently participating in a programming contest (http://contest.github.com), which has as goal, to create a recommendation engine. I started coding in ruby, but soon realised it wasn't fast enough for the algorithms I had in mind. So I switched to C, which is the only non-scripting language I know. It was fast, of course, but I cringed every time I had to write a for loop, to go through the elements of an array (which was very often).
That's when it dawned: I wish I knew a fast, yet high-level language, to program all these intensive computations with ease!
So I looked at my options, but there are a lot of options these days! Here the best candidates I've found over the months, with something which bothers me about each of them (that hopefully you can clear up):
Clojure: I'm not sure I want to get into the whole lisp thing, I like my syntax and cruft. I could be convinced, though.
Haskell: Too academic? I don't really care for pure functional, I just want something which works. But it has nice syntax, and I don't mind static typing.
Scala: Weird language. I tried it out but it feels messy/inconsistent to me.
OCaml: Also wondering if this is too academic? The poor concurrency support also bothers me.
Arc: Paul Graham's lisp, too obscure, and again, I'm not sure I want to learn a lisp. But I trust this man!
Any advice? I really like the functional languages, for their ability to manipulate lists with ease, but I'm open to other options too. I'd like something about as fast as Java..
The kind of things I want to be able to do with lists are like (ruby):
([1, 2, 3, 4] - [2, 3]).map {|i| i * 2 } # which results in [2, 8]
I would also prefer an open-source language.
Thanks
Out of the languages that you've listed, neither Haskell nor Arc match your "fast" requirement - both are slower than Java. Your idea that Haskell is faster than Java and approaches C is most likely coming from one well-known flawed test that tried to measure performance by implementing sort. One thing that they've missed is that Haskell is lazy, and thus you need to use the results of the sort for it to actually perform that; and they measured performance simply by remembering current time, "calling" the sort function, and checking the time delta. C version of the test faithfully performed the sort, Haskell version simply returned a thunk for lazy evaluation which was never called.
In practice, there are a number of reasons why Haskell cannot be that fast even in theory. First, because of pervasive lazy evaluation, it often cannot pass around raw values, and has to generate thunks for expressions - the optimizer can trim down on those in trivial cases, but not for more complicated ones. Second, polymorphic Haskell functions are implemented as runtime-polymorphic, and not like C++ templates where every new type parameter instantiates a new version of code that is optimally compiled. Obviously, this necessitates extra boxing/unboxing. In the end, Haskell will struggle to beat any decent VM (such as HotSpot JVM, or CLR in .NET 2.0+), much less C/C++.
Now that's settled in, let's move on to the rest. Scala uses JVM as a backend, and thus is not going to be any faster than Java - and if you use higher-level abstractions, it will most likely be slower somewhat, but probably in the same ballpark. Clojure also runs on JVM, but it's also dynamically typed, and that carries an unavoidable performance penalty (I heard it does clever tricks to mitigate that to some extent, but some of it really is unavoidable no matter what).
That leaves OCaml, and out of your list, it is the only language that had actually been conclusively shown to reach the performance of C/C++ compilers on valid tests. It should be noted however that this would not be typical of idiomatic OCaml code - for example, its polymorphism is also runtime, similar to Haskell, and that carries the appropriate penalty; also, its OOP system is structural rather than nominal, which precludes an optimal vtable-based implementation; so that is going to be slower than C++, too (I'd expect perf penalty close to that of Objective-C dispatch compared to C++ dispatch, but I don't have any numbers to back that up). So you can beat C++ in OCaml if you steer away from certain language features, but unfortunately, it's those features that make OCaml so attractive in the first place.
My advice would be this: if you really need speed, go with C++. It can be fairly high-level if you use high-level libraries such as STL and Boost. It doesn't have some high-level language abstractions you might be used to, but libraries can compensate for that - sometimes fully, sometimes in part. For example, you don't have to write a for-loop to iterate over an array - you can use std::for_each, std::copy_if, std::transform, std::accumulate and similar algorithms (which are mostly analogous to map, filter, fold, and similar traditional FP primitives), and also Boost.Lambda to cut down on boilerplace.
Why not simple Java or C#? Should be faster then Ruby, more high level then C and have a huge userbase.
Your criticism of pretty much everything seems to be that it's "weird" or "too academic." But what does that mean? It's the sort of vague criticism that you can throw at any unfamiliar language that isn't totally mainstream (i.e., not C, C++, Objective-C, Java, Ruby, Python or PHP). There's nothing about all those languages that's inherently good for academia and bad for anything else. Try to break down your analysis a little further: Specifically, what is it that troubles you about those languages? You might find that your brain is just instinctively pushing away something unfamiliar. If that's the case, learning one of those languages might be a good way to expand your mind.
Alternatively: It sounds like you're looking for a functional language, so you might look at F#. It's a first-class CLR language created by Microsoft, so it doesn't carry any "academic" mental baggage, and it's very similar to OCaml.
newLISP is fast, small, integrates extremely easily with C, and it has quite a few statistical functions built-in.
Haskell is my current preference as a performant, high-level language. I've also heard very good things about OCaml, but haven't personally used it much.
Scala and Clojure will have similar performance to Java -- slow, slow, slow! Sure, they'll be faster than Ruby, but what isn't?
Arc is a set of macros for MzScheme, and is not particularly fast. If you want a performant LISP, try Common LISP -- it can be compiled to machine code.
How about Delphi / FreePascal? They're native code & fast. I do a lot of real-time graphics & processing with them. They dont require that you work 'low level', but you can if you need to. Plus you can embed assembler if needed for extra performance. FreePascal is cross platform if you want to stay off Windows.
D might fit the bill? Compiles to machine code but allows for programming using higher-level concepts.
Python can be made to run fast, especially using the NumPy package. Relevant links below:
http://www.scipy.org/PerformancePython
Cython and numpy speed
You seem uncomfortable with any language that doesn't look like one you already use. That's going to limit you, so I'd suggest one you won't be comfortable with if you're interested in expanding your horizons. I'm not saying you'll want to continue with any particular language (I have a definite preference never to touch Tcl again), but you should try it sometime.
There are nice fast implementations of Common Lisp, and that's an easy language to write functional programs in. Besides, if you can get along with it, you'll find a lot of neat things you can do with it.
Computation? Fortran. Beats the pants off of anything else.
If you don't mind .NET...
F# - based on O'Caml, multiparadigm language with full access to .NET Framework. Included officially in .NET FW 4.0
Nemerle - see F# and add to that a POWERFUL metaprogramming capabilities.
After your update:
If you want to manipulate lists easily you should go with Common Lisp. It is only 2 times slower that C in average (and actually faster in some things), it is great for list processing and it is multi-paradigm (imperative, functional and OO) - so you don't have to stick to functional-only programming. SBCL is a good Common Lisp to try first, IMO.
And don't get bothered by strange "lispy" things like parentheses. It is not only quite stupid to judge language by its syntax, rather than semantics, but also parentheses are one of the greatest strengths of LISP, because they eliminate differences between data and expressions and you can manipulate language itself to make it fit your needs.
Don't listen to people who advice C++/C#/Java. Java functional part is non-existant. C++ functional part is terrible. C# delegates makes me sick because of their complexity. They are not REAL multi-paradigm imperative/functional languages, they are imperative/OO languages that have some small functional bits, you can't do real functional programming in them.
C++ or alternatively C# and mono.
Honestly, to accomplish much in the world of software engineering, you will likely have to wrap your head around these languages you find distasteful. Java, C, C++, C#, etc. are likely to come up in a career that involves programming.
Looks like you've done some interesting work. I encourage you to push your technical skills harder. It will be worth the effort.
Alternatively, Python might be good, given your interests. You might find Smalltalk interesting, or even ATS.
For some ideas, look at the Language Shootout and analysis by Oscar Boykin. You have already discovered this, but comparing Ruby to C we see that Ruby is between 14 and 600 times slower (several tests are more than 100 times slower). He also points out that Python is faster than Ruby. The benchmarks for all languages is interesting.
Also interesting are benchmarks from Dan Corlan.
You might consider python; it supports writing modules in C or C++, so you can get it working in a high-level language, profile it, rework the algorithms, and if it still isn't fast enough, translate the hotspots to C or C++ for speed.
Consider Tcl, combined with C. Do the really compute-intensive stuff in C since that's what you know how to do, then use Tcl as the glue to combine the high level code with your C-based code.
I make this recommendation not because Tcl is necessarily the best language for the job (there really is no "best" for something like this) but because you'll learn a lot about the concept of combining the strengths of two different languages. It's an important technique that could serve you well in your career whether it's Tcl/C, Lua/C, Groovy/Java, Python/C, etc.
Python with pyrex or psyco may be a better fit? Probably not as fast as C, but you can see some significant speedups from regular Python.
If you want something that's "about as fast as Java," the obvious solution is JRuby.
If you install Netbeans (use the download button under the Ruby column), JRuby is the default interpreter. It doesn't get much easier!
If your problem is C's clunky loops, I'd suggest looking at Ada. It allows you to loop through a whole array with a simple statement like so:
for I in array_name'range loop
--'// Code goes here
end loop;
For AI projects, I'd also suggest you look into using Clips, which is a freely-available inference engine.
Rather than OCAML, you might consider F# -- it's source compatible with OCAML (or you can use a lighter weight syntax) and it supports actor-style concurrency with what it calls asynchronous workflows (which are really an almost-monad for applying asynchronous execution).
Not that -- as Scala shows -- you need to have actor style concurrency baked into the language, if you build it into a library. The rest is just syntactic sugar.
Learn C++ and familiarize yourself with its standard library. It won't be that hard to learn as you already 'speak' C, but keep in mind that C++ is not just a better C, it's another language with its own concepts and methods.
Why not Erlang?
It's not too much like the languages you already know, so you can learn new concepts
It has some interesting capabilities for multiprocessing
It's not out of academia. Erlang was a commercial language first.
There are at least two significant open source applications written in it: CouchDB and Wings3d
I believe going through C C++ and Java or .net then moving on from here to any one way java or .net , because c is more machine oriented and C++ and java will give you hands on with object oriented learning, then later on switching to python (to really appreciate the clean code than in C C++ and JAVA ).
I am attempting to determine prior art for the following idea:
1) user types in some code in a language called (insert_name_here);
2) user chooses a destination language from a list of well-known output candidates (javascript, ruby, perl, python);
3) the processor translates insert_name_here into runnable code in destination language;
4) the processor then runs the code using the relevant system call based on the chosen language
The reason this works is because there is a pre-established 1 to 1 mapping between all language constructs from insert_name_here to all supported destination languages.
(Disclaimer: This obviously does not produce "elegant" code that is well-tailored to the destination language. It simply does a rudimentary translation that is runnable. The purpose is to allow developers to get a quick-and-dirty implementation of algorithms in several different languages for those cases where they do not feel like re-inventing the wheel, but are required for whatever reason to work with a specific language on a specific project.)
Does this already exist?
The .NET CLR is designed such that C++.Net, C#.Net, and VB.Net all compile to the same machine language, and you can "decompile" that CLI back in to any one of those languages.
So yes, I would say it already exists though not exactly as you describe.
There are converters available for different languages. The problem you are going to have is dealing with libraries. While mapping between language statements might be easy, finding mappings between library functions will be very difficult.
I'm not really sure how useful that type of code generator would be. Why would you want to write something in one language and then immediately convert it to something else? I can see the rationale for 4th Gen languages that convert diagrams or models into code but I don't really see the point of your effort.
Yes, a program that transform a program from one representation to another does exist. It's called a "compiler".
And as to your question whether that is always possible: as long as your target language is at least as powerful as the source language, then it is possible. So, if your target language is Turing-complete, then it is always possible, because there can be no language that is more powerful than a Turing-complete language.
However, there does not need to be a dumb 1:1 mapping.
For example: the Microsoft Volta compiler which compiles CIL bytecode to JavaScript sourcecode has a problem: .NET has threads, JavaScript doesn't. But you can implement threads with continuations. Well, JavaScript doesn't have continuations either, but you can implement continuations with exceptions. So, Volta transforms the CIL to CPS and then implements CPS with exceptions. (Newer versions of JavaScript have semi-coroutines in the form of generators; those could also be used, but Volta is intended to work across a wide range of JavaScript versions, including obviously JScript in Internet Explorer.)
This seems a little bizarre. If you're using the term "prior art" in its most common form, you're discussing a potentially patentable idea. If that is the case, you have:
1/ Published the idea, starting the clock running on patent filing - I'm assuming, perhaps incorrectly, that you're based in the U.S. Other jurisdictions may have other rules.
2/ Told the entire planet your idea, which means it's pretty much useless to try and patent it, unless you act very fast.
If you're not thinking about patenting this and were just using the term "prior art" in a laypersons sense, I apologize. I work for a company that takes patents very seriously and it's drilled into us, in great detail, what we're allowed to do with information before filing.
Having said that, patentable ideas must be novel, useful and non-obvious. I would think that your idea would not pass on the third of these since you're describing a language translator which would have the prior art of the many pascal-to-c and fortran-to-c converters out there.
The one glimmer of hope would be the ability of your idea to generate one of multiple output languages (which p2c and f2c don't do) but I think even that would be covered by the likes of cross compilers (such as gcc) which turn source into one of many different object languages.
IBM has a product called Visual Age Generator in which you code in one (proprietary) language and it's converted into COBOL/C/Java/others to run on different target platforms from PCs to the big honkin' System z mainframes, so there's your first problem (thinking about patenting an idea that IBM, the biggest patenter in the world, is already using).
Tons of them. p2c, f2c, and the original implementation s of C++ and Objective C strike me immediately. Beyond that, it's kind of hard to distinguish what you're describing from any compiler, especially for us old guys whose compilers generated ASM code for an intermediate represetation anyway.