Let's make an on-topic place to discuss programming language relevant issues in concurrency and non-determinism. Software development in general isn't really on topic. It really needs to be about an aspect of PL design or implementation, or else LtU isn't suitable.
It seems folks designing a PL would like a language to be suitable for performance work, in a world where scaling better may imply doing more things in parallel, to get more hardware usage per unit of time in lieu of processors actually running faster. The plan is something like: well if cycles have stalled we can just use more cores. In general this seems to lead to unpredictability, which perhaps might be addressed by PL tech, somehow or other.
Something is missing in how developers specify what they think code will do, in the large. It's a common belief it will be obvious. ("It should be obvious what the code does from reading it, so comments are superfluous.") This is slightly like thinking other people will recognize a tune you have in mind when you drum out its rhythm with your fingers, when in fact they will only hear you drumming your fingers. A pattern you expect to be obvious won't be.
Maybe more than one layer of grammar would help. (Just an idea.) In addition to local language syntax, you could specify larger patterns of what will happen, in terms of expected patterns in future inter-agent transactions, whether they be objects or something else. There seems lack of current art in capturing developer intent about shape of event sequences. Sometimes I suspect a few people intend to fix this with determinism in language behavior, which doesn't seem a good fit for fallible distributed internet components.
I have nothing to post unless a remark catches my eye. If I have something interesting to say, I will. (I don't blog any more, and I'm all but unreachable except here, unless you call my phone or email my work address. My online presence is near zero. I don't even check LinkedIn.)
What specifically would you do to a programming language to address the emergent elephant that results from code specifying tail, legs, trunk, etc?
A paper presented as a poster at ICML. Abstract:
Also comes with reviews.
Hi, I have been pondering what I want to do for my master
My idea is to write a source-to-source compiler from a Lisp_2 to
Below is a rough draft for the introductory chapter. Beware that
Imbuing Lisp with the thread-safety guarantees of Rust by using a source-to-source compiler.Introduction
This short introductory chapter starts by presenting the question we are trying to answer, followed by a summary of our suggested solution that provides a definitive answer to the our question. We end this chapter ends with an overview of the subsequent chapters.The question
By compiling a language
A commonly selected target language for a transpiler is the programming language "C". Since C is available on practically any machine, the C-code that is generated from a program written in
Moreover, any optimizations that the C-compiler can achieve are automatically and implicitly available to the source language
In the case of C there are numerous pain-points such as pointers running amok and its lack of built-in garbage collection. If the source-language is a garbage-collected language, that is type-safe, such problems have to be addressed in the source-to-source compiler.
Furthermore there are certain limits imposed on our source language by the limitations of C has, such as a maximum of 32 arguments in function calls or less than 16 levels of lexical blocks.
Inherently, each source language presents its own set of advantages and negative consequences with respect to the source language.
The Rust programming language, which is a systems programming language that is a contender in the same domain as C and C++, has the desireable attribute of guaranteeing thread-safety and threads without dataraces.
The question then is, can a specific source language compiled into Rust be unequivocally determined to be thread-safe through the merits of the source-to-source compiler alone?The solution and answer
In this text we present a source-to-source compiler from a Lisp2 dialect to Rust whereby we can, through the use of the Rust compiler
Since there is no additional body of work this subsection cannot be fully written, but a rough layout of the remainder of the text would probably look like:
Chapter 1. An overview of Lisp and a formal description of our dialect as well as an overview of our concurrency model (not sure if the latter is necessary)
Chapter 2. A precursory introduction to Rust with references to papers demonstrating the validity of the claims that Rust provides thread safety guarantees and data race guarantees as this is a corner stone to our work.
Chapter 3. Examples from concrete programs written in the Lisp dialect that will serve as benchmarks when evaluating the code generated by our compiler.
Chapter 4. An overview of the implementation of the compiler that also discuss alternative implementation choices and why they were not chosen
Chapter 5-(maybe several chapters): Explanations describing the parts of the different compilation phases. It is probable that we will encounter some automatas here.
Chapter 6: Code generation optimizations and translation strategies to portable Rust code.
Chapter 7: Evaluation of benchmarks
Chapter 8: Discussions of possible applications, such as tiering source-to-source compilers in a layered fashion to successively imbue desireable traits from each language in the compilation sequence to the top-most source language.
Appendices: Complete source code for the compiler
I'm building a relational language. I like the idea of a static type system but after toying for a while with the interpreter I have wonder how feasible is it.
Here, I think a "type" is the whole head of the relation (even scalars as "1" are relations) and most thing fell fine, but the join operator cause trouble: It could merge heads (or not) depending in the kind of join. So, I'm saying that I feel the relational mode generate on the fly new types and can't be specified before.
So, If i have a query like:
city where .id=1
I see the type of each relation change. Is impractical to type by hand each combination, but I like the idea of type most of it. But can the compiler be made to work with this similar to ML?
How work the sql languages, them are dynamic?
In some literature, including Wikipedia, there is a distinction I don't quite understand made between iso-recursive and eqi-recursive typing. In both cases, however, there is a concept of unrolling a recursive type by replacing the fixpoint variable with the recursive term.
I believe this idea is suboptimal and should be replaced by a better one I shall describe below. I am interested if this has been done before, and if my analysis (and the concrete algorithm I have written) is correct.
The problem with iso-recursion is that it induces an equivalence relation on type representations, and this a partition, which fails to place eqi-equivalent types in the same class. Here is an example:
( -> [( -> fix-2)])
Here [..] denotes an n-ary tuple type, -> is a function type, and fix-2 is a fixpoint whose binder is implicitly 2 levels up in the structure. These encodings represent the same type, the second one is recursive but its unrolling is not equal to the first type.
I have found a solution to this problem: instead of a full unrolling, we can just unroll one level. This is much better! In particular my re-rolling algorithm subsumes the standard re-rolling by a full circle, and also produces a unique canonical representative of the class. It should work for monomorphic and first order polymophic types, at least if there is only a single fixpoint.
I will not give the algorithm here but I will give a description because it is fun! Consider a piece of string representing your type, with coloured segments for each level. The end of the string is knotted around the string some way up. The knot is called the fixpoint and the place it is knotted to is called the binding point.
The algorithm for re-rolling the string simply rolls the circle up the string one segment and compares the colours. If they're equal, roll up another segment. Continue until you either run out of string, or you get a mismatch, in which case backtrack by one. You can finish by cutting the matching tail off and doing a new knot.
Unrolling is the same. Just unroll ONE segment to shift the fixpoint binder down out of the way.
A standalone demo in Ocaml is here:
Finally, my prayers are being heard. The question was "get us web enabled bytecode" and the answer came from above in a form of W3C group effort, WebAssembly.
Though it encapsulates low level jump commands into structures controlled by labels (I'd like to leave it at the low level for maximum freedom), it is more or less what I'd expected from a bytecode that could be ran inside browser. It's enough assembler like language to leave a lot of space for specific implementation of different programming language architectures, while retaining speed of native implementations. Maybe it is an overkill for a bytecode language to automatically deal with functions (see "call" command), but it can't hurt, we dont have to use it, we can maintain our own call stack if we want to replace existing one.
It is ought to have continuous memory handler that indexes space from 0 on. This memory can even grow on the fly, if we want to. This is just what I need, encapsulation of memory management.
If this is what I'm thinking it is (nearly 1:1 mapping from bytecode to machine code upon compilation), I can say only one thing: "thank you, world :)"
Tofte and Talpin used stack of regions for managing memory. Can you recommend papers where per-frame regions/heaps are used for managing effects?
This is an older paper about metaprogramming and it ties into open source development process and why metaprogramming requires free/open source software.
The beginning of the article outlines a list of types of metaprograms such as compilers/translators, phase splitters, code walkers, meta compilers,explainers, etc. Later on it says that metaprogramming is required as problem complexity increases and there are more actors/stakeholders involved.
In statically typed languages or at least in better IDEs, it's possible to perform various refactorings across a codebase which can constitute metaprogramming in a crude respect:
I'm designing a Turing complete utility microlanguage that has a minimal set of commands. Chosen commands should on the one side have ability to compile to fast assembler code, and on the other side sould be enough descriptive so one can directly write sane code with them.
So I'm thinking about a minimal set of commands. Somehow I think it should be imperative language, because microprocessors work that way at low-level understanding. I was thinking of supporting only these:
Do these commands sound cool or there is something that can be changed for better speed/usability performance?
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