http://clhs.lisp.se/Body/f_cmp.htm

In fact, with the package system ASDF, you can recompile (incrementally) an entire package at runtime. This is a single blocking function call; something like:

(asdf:operate 'asdf:compile-op :my-package)

I have a web project where any request in dev mode triggers a system recompilation only if the git revision of the working tree is new.

(my-handler :did-recompile (when (revision-is-new) (recompile) t))

That recompiles the system including MY-HANDLER, and right after RECOMPILE returns, the new version of MY-HANDLER from the working tree will be active.

The way Common Lisp lets me do that as a ten minute hack feels like living in the future... except of course it's pretty old technology!

Edit: I realize this is not really what you are talking about as "self-modifying code." Having full access to the compiler at runtime is a good first step for doing some of what you want, though. And with S-expressions, constructing and manipulating "ASTs" is ridiculously straightforward.

All the pieces are there.

Of course the JITer will not perform the same level of optimizations as the fullblown code generator, but then you can just call that if you like.

The new JIT engine does support SIMD [1]. And C# can generate SIMD code using various libraries (I think MS has one, and I know Mono does).

And various people have shown how to do fullblown x86 assembly code generation and execution from within C#, but it's fragile.

[1] http://blogs.msdn.com/b/dotnet/archive/2014/04/07/the-jit-fi...

            float[] floats = new float[1000];
            float factor = 1.01f;
            int index = 0;
            while (index < 1000)
            {
                floats[index++] *= factor;
            }

00007ff8`80a804a9 488d549010 lea rdx,[rax+rdx*4+10h]

00007ff8`80a804ae c4e17a1002 vmovss xmm0,dword ptr [rdx]

00007ff8`80a804b3 c4e17a590524000000 vmulss xmm0,xmm0,dword ptr [00007ff8`80a804e0]

00007ff8`80a804bc c4e17a1102 vmovss dword ptr [rdx],xmm0

This is in VS 2013, compiled with DEBUG off, prefer x86 off, and 'any cpu' as the target.

- Use the new RyuJIT

- Make use of 64 bits CPU

- Use the vector and matrix classes from System.Numerics

Unless you're optimising for size, SMC'ing little pieces is definitely going to be slower. But e.g. in loops that do a few hundred iterations, saving a cycle or two by getting rid of some opaque predicates quickly adds up and the cache/pipeline-flushing overhead (few hundred cycles at most) becomes insignificant.

After all, as the parent comment says, a JIT is basically SMC'ing huge blocks of code, and it's definitely faster than the equivalent alternative of a bytecode interpreter.

See the LLVM "Kaleidoscope" tutorials from the LLVM docs. They implement a simple toy compiler with a JIT-based REPL. Basically you use the LLVM framework to build a program and then run it through the compiler pipeline and get a callable function pointer to your newly compiled function(s), optimized for the CPU architecture you're running on.

Even if that remotely made any sense, which i don't think it does... c code compiles to the end target of all jits anyway, you just have some if statements or use pointers to other executable code that you swap around. Not only do you get the executable code as efficable as any jit, its constant with no jit cost. Its called c programming.

What OP wants is a way to get the advantage of ahead-of-time compilation for the 99% of the code that benefit from it, and the advantages of JIT for the remaining 1% (or even less).

However, I'm not sure how feasible that would be.

How much it would help performance in practice I couldn't say.

... then the high-level language isn't expressing self-modifying; the compiler is doing it to optimize the code while preserving the abstract meaning that is free of self-modifying.

From a certain vantage point, in these languages, if you aren't seeing assembly from time to time, you're not seeing reality.

Consequently, I kind of chuckle when I hear people say they can't debug optimized builds.

http://www.dadhacker.com/blog/?p=1911

That project was using a CPU costing less than twenty cents to control the power of a consumer product. Code space mattered a lot, and doing the project entirely in a high-level language would have doubled the part cost. When you're talking quantities in the tens of millions, saving ten or twenty cents on the cost of goods is a Big Deal.

The article is begging the question. I'm unaware of anyone who thinks assembly is not relevant.

Blackbox and reversing, though, certainly need or benefit from assembly. Depending one what one is analysing.

Since these days I'm a web developer I'm at a level in the stack where using Assembly would be alien and frankly I doubt I could anyway without some serious study.

They call javascript the "assembly" of the web, yeah certain subsets of programmers are interesting in their beliefs.

However, even students do need assembly language when they take their computer architecture, operating systems and compilers classes. And some students will probably end up to do compilers or operating system work professionally at some point in their careers.

Assembly language is still a very valuable skill although a few people will ever write any code by hand. But reading assembly code as well as writing programs that emit assembly code will always stay relevant.

The true masochists continue to x86 in the higher level courses.

That is higher than the going rate for Haskell in finance afaik.

So yes, still relevant.

I used to work with Haskell in finance, but as an employee not contractor. Money was OK, but not higher than for any other language as far as I can tell.

(I wouldn't be surprised if going rates for Cobol and Fortran were higher than for any sane language.)

General advice for deeply technical consulting: you need to have a lot of deep practical experience in a few specific areas and you'll generally need to hit the ground running no matter what project you're dropped into and rapidly start generating corresponding value for the client. And expect to be continuously fighting off offers of permanent employment once you start picking up work.

That's why I tell people who want to be rich or powerful to master people skills, maintain right image, go to right schools, get the right connections, and deal/negotiate their way to top manager by manger, boardroom by boardroom.

(I'm not criticizing your conclusion, just your argument)

Oh grow up

For others?

Which group of people or school of thought would say that assembly isn't relevant? I'm genuinely curious.

Just 5-10 years ago, that might have been considered a joke. Now I wonder if you're referring to a specific project. And if it's already deployed as a Droplet. ;)

Text editors are pretty tame beasts by comparison.

Which was it?