coherence VS xvm

There are a few different tool-sets for producing Java byte code. I'm not sure which one to suggest, because back when I last needed one (end of '96), there were none, so I wrote my own. But I assume that most people use ASM or something similar.

This is one that I like a lot. Years ago (1997 timeframe) I had implemented it in a Java compiler, and a few years later in a Java library (https://github.com/oracle/coherence/blob/4e6e343e1ffd9bbfea3...) that would create an exception on the assertion failure and parse its stack trace to find the source code file name, and read it to find the text of the assertion that failed, etc. so it could build the error message ...

In Ecstasy, we built the support directly into the compiler again:

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For the debugger (but not required by the runtime), there is an optional table that points to the ranges of ops at which names and types are bound to registers

FWIW - here's an AST for Java that directly emits Java byte code: https://github.com/oracle/coherence/tree/master/prj/coherence-core/src/main/java/com/tangosol/dev/compiler/java

It has been "experimented with" many times. Here's an example from TDE, a component-based development environment from Tangosol (now part of Oracle).

If it helps, here's a Java recursive descent parser that I wrote years ago.

If you want to see an example, here's a Context interface from a multi-language compiler framework (compiling multiple different languages to Java byte-code) that I wrote years ago.

I built an entire Java compiler in four months, from scratch, by myself, over twenty years ago. (Now owned by Oracle; still used today. Thank you, Larry.) But starting from a well written spec for a simple language like Java is orders of magnitude easier than developing a new language, runtime model, and tool-chain from scratch.

As mentioned, the various parsing methods each contribute back an AST node, so on the way down the recursion, they are parsing, and on the way back up from the recursion, they are building the tree. Here's a fairly simple recursive descent Java compiler written in Java that I wrote a few years back, in case you are looking for an example.

If you're curious how some of this can be implemented in a Java compiler, I wrote one years ago. For example, checking that the left side is an l-value:

Have a look at the ecstasy library for the language definitions of these types.

2) Funky interfaces: This is an Ecstasy interface that declares abstract static members (e.g. functions), which can then be implemented on any class and overridden on any sub-class, such that they can be invoked by type (instead of this), and virtually resolved (late bound at runtime) based on the type known at compile time. The best known example, of course, is Hashable, because it has to guarantee that a type implements both equals() and hashCode() on the same class, and the implementation is tied to the type, and not to the this. (C# added a similar feature last year in version 11.)

I'm just going to warn you in advance that invocation is one of the hardest things in the compiler to make easy. In other words, the nicer your language's "developer experience" is around invocation, the more hell you're going to have to go through to get there. The AST nodes for Name( (NameExpression) and Invoke( (InvocationExpression) alone are 7kloc in the Ecstasy implementation, for example -- but the result is well worth it.

Ecstasy uses message passing automatically behind the scenes for asynchronous calls, but the message passing isn't visible at the language level (i.e. there is no "message object" or something like that visible). Basically, all Ecstasy code is executing on a fiber inside a service, and services are all running concurrently, so from any service realm to any service realm, the communication is by message.

Regarding Ecstasy, we did not set out to build a new language; we actually set out to solve a real world problem. Specifically, we wanted to be able to dramatically improve the density of workloads in data centers, by at least two orders of magnitude in the case of lightly used applications. Our initial goal was to create a runtime design that would support 10,000 stateful application instances on a single server. Let's call it the "a10k" problem 🤣 ... a tribute to the c10k problem from 1999. We refer to our goal as "zero carbon compute", i.e. we want to push the power and hardware cost for an application to as close to zero as possible; you can't reach zero, but you can get close. If we succeed, we will help reduce the electricity used in data centers over the next few decades by a significant percentage.

Generally, left to right, one character at a time. If you’re looking for example code, here’s a simple hand-built lexer.

Parts of Ecstasy are now implemented in Ecstasy. Here's the Lexer, for example.

Ecstasy

Ecstasy and the xvm were designed assuming an adaptive runtime compiler (similar in concept to the Hotspot compiler for Java), but not necessarily using a JIT.

A Future reference has the various capabilities that you'd imagine, taking lambdas for thenDo(), whenComplete(), etc. The reference, in the above example, is a local variable, so you just obtain it using the C-style & operator: