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The Open Source Survey asked a broad array of questions. One that caught my eye was about problems people encounter when working with, or contributing to, open source projects. An incredible 93 percent of people reported being frustrated with “incomplete or confusing documentation”.
That’s hardly a surprise. There are a lot of projects on Github with the sparsest of descriptions, and scant instruction on how to use them. If you aren’t clever enough to figure it out for yourself, tough.
[...] According to the Github Open Source Survey, 60 percent of contributors rarely or never contribute to documentation. And that’s fine.
Documenting software is extremely difficult. People go to university to learn to become technical writers, spending thousands of dollars, and several years of their life. It’s not really reasonable to expect every developer to know how to do it, and do it well.
-- submitted from IRC
(Score: 2) by hendrikboom on Tuesday June 06 2017, @02:08AM (6 children)
There are two interesting Lisps; both of them are Scheme implementations.
(1) Racket: Racket's specialty is multilingual programming. You can define new syntaxes and new semantics (i.e. new languages) and compose a program from modules written in those languages. The feature seems to cover everything from minor tweaks to completely different languages. For example, you can write modules in Algol 60 or in Scribble. Scribble is a notation for Scheme that looks and feels like a text formatting markup language.
And Racket has excellent tutorials and documentation and a supportive mailing list, to return this discussion to the original subject.
(2) Gambit. Gambit is a Scheme implementation that compiles directly to C (or C++) (Or you can just use the interpreter). Its virtue is that you can actually introduce new features and specify just what C code is to be generated from it. As a bonus you get a rather flexible scripting language. And you get to use low-level Cisms when you want.
-- hendrik
(Score: 2) by kaszz on Tuesday June 06 2017, @03:20AM (5 children)
Do any of these LISPs make efficient use of multi cores that are common now, but were not when those languages came into being? They should be able to exploit that even better than many other languages simple by their nature.
(Score: 2) by DannyB on Tuesday June 06 2017, @02:17PM (1 child)
I would agree that Racket and Gambit are interesting. If you are interested in Scheme. There is also Chez Scheme, which was commercial, but then became open source.
https://en.wikipedia.org/wiki/Chez_Scheme [wikipedia.org]
http://www.scheme.com/ [scheme.com]
https://github.com/cisco/ChezScheme [github.com]
Incremental native-code compilation to produce native binaries for the PowerPC, SPARC, IA-32, and x86-64 processor architectures. Chez Scheme supports R6RS.
Chez Scheme has a windowing and graphics package called the Scheme Widget Library, and is supported by the portable SLIB library.
I like Clojure. (clojure.org) Clojure is a modern lisp. It has reach, it runs on: JVM, JavaScript, .NET. Clojure runs on JVM and .NET, while ClojureScript compiles to JavaScript and runs in-browser or other JavaScript implementations.
Momentary sidetrack on JVM (Java Virtual Machine) . . .
JVM is the runtime engine that runs Java Bytecode which is emitted from the Java compiler, Clojure compiler, and other language compilers (Kotlin, Scala, Groovy, Jython, JRuby etc).
JVM is interesting because it is an industrial strength runtime platform. A decade and a half of research has gone into JVM's JIT compilers C1 and C2, and it's multiple GC's. When you run JVM you can select "server" mode or "client" mode (eg, tune it for running on a workstation or on a server). You have a choice of GC algorithms to pick from, and gobs of GC tuning parameters. If you simply give it plenty of RAM, JVM is very fast. The GC's run in parallel on multiple CPU cores. So if you throw plenty of CPU cores at it, you may never see any GC pause times.
You can get multiple implementations of JVM. Oracle. Or Azul's Zing -- which is a free binary build (with source) based on the open source OpenJDK. (Also Oracle's Java is based on OpenJDK) If you're on IBM mainframe hardware, then IBM provides Java runtime. Java runtime is available on Raspberry Pi. Languages that compile to JVM can be used for Android development (which compiles JVM bytecode into Dalvik bytecode to run on Android).
Java (or rather JVM and various languages) are popular in enterprise software. Java is used for high frequency trading (yes really).
If you need a JVM that runs on hundreds of GB of RAM, and with up to 768 cpu cores, then look at Azul Zing on Linux.
We now return to Clojure . . .
Without being grandiose, Clojure runs on an ordinary desktop java runtime, even on a humble Raspberry Pi.
Clojure is functional programming.
All data in Clojure is immutable. That means you can't alter anything in a data structure. If I have an array of 50 million elements, and I change element 1,253,507; I get back a new array with that element changed. The original array is unaltered. Yet the performance guarantee is "close to" what you expect of arrays for indexed access. How is this magic implemented behind the scenes? With 32-way trees. When you changed element 1,253,507, a certain leaf node in the tree was changed. That new node, along with new nodes all the way up to a new root node become the new array. The tree shares structure with all other tree elements of the old array. Thus only a few tree nodes are recreated at a cost of Log32(n). So it's close to direct indexed performance for the huge benefit of immutable data structures. This means there is no such thing as: (SETF (CADR x) 'foo) That would be trying to surgically modify a data structure. There are similar operations that can do this, but they re-construct the portions of the data structure, which ultimately makes use of the underlying (invisible to you) implementation of immutability.
All variables are final. (Meaning, once a variable is assigned a value it cannot be changed to a different value.)
This may sound restricting, but Clojure definitely has the right constructs to give it a functional style that mitigates what you might think of as restrictions. The end result is better quality code. You can see Haskell inspiration.
Clojure has primitive types for Lists, Arrays, Sets and Hash Maps. Lists are what you already know. Arrays are what you expect. You can alter any element in the array by direct index, far cheaper than in a list, but with the guarantees of immutability of the original array (you get back a new array with the single element altered). Sets are what you expect. Sort of like an array or hash map, an item can only occur once in the set. Hash Maps are key-value stores like in many modern languages, but backed by an implementation that uses different backing for different sized hash maps. A small hash map of a dozen items will not use hashing, but merely be internally an array where the key array is searched for the key. At some invisible magic threshold the underlying implementation becomes a hash map. Clojure has lots of hidden implementation optimizations, like for short lists, arrays, etc. Implementations of functions with certain common parameters.
Clojure has excellent Java interoperability (when used on Java). Think of this like other lisps having an FFI to C. Clojure and Java (or other JVM language) code is fully interoperable. Clojure data structures can be passed to Java and manipulated or even created in Java by importing the Clojure imports into Java code to be able to access the Clojure data structure APIs. Java data structures can be passed to Clojure and accessed with dot notation to access methods and class members. You can write JVM classes in Clojure for compatibility with other Java code. For example, if using a Java library that needs to be passed a callback function, it is easy to write this callback function in Clojure without using any Java.
Because it runs on JVM, Clojure has access to the EMBARRASSINGLY large amount of riches of Java libraries. Code to do anything under the sun. Including access to the GPU. And there are Clojure libraries for working with the GPU.
Clojure has an excellent story about concurrency. I won't go into it here. But you can write high level code that will run on all your CPU cores. In Clojure, MAP is like MAPCAR in CL. Instead of using "map", you can use "pmap" to process concurrently if you don't care about the order of the returned elements. (eg, I have a list of ten million items, and I need to run function F on all of them, I can use (pmap F items) if I don't care that the returned list is in a different order than items. Watch all your CPU cores light up.)
Clojure has a nice syntax for Arrays, Sets and HashMaps. Thus you can render arbitrarily complex data structures to text, and then back to internal data again. Think JSON but much better.
You'd be amazed with what people do in Clojure because of Java interop. Playing with MIDI and synthesizers, even software synthesizers. See Clojure's interface to Overtone. Using Clojure with OpenCV (computer vision).
Let me throw out another interesting one.
Pixie Lisp
It compiles to native code. Built with the Rpython tool chain. Has good C FFI because of this. Early implementations on Raspberry Pi with direct Lisp access to WiringPi which provides access to the hardware GPIO pins (digital / analog / SPI / I2C / PWM input and output pins).
Pixle lisp is also Clojure inspired.
Finally, let me mention: Shen, a sufficiently advanced Lisp.
(to be indistinguishable from Magic. See that it is like having Haskell and Prolog baked into the Lisp itself.)
Hope that helps.
To transfer files: right-click on file, pick Copy. Unplug mouse, plug mouse into other computer. Right-click, paste.
(Score: 2) by DannyB on Tuesday June 06 2017, @02:19PM
Duh. "Or Azul's Zing -- which is a free binary build" I meant Azul Zulu.
Zing is the one that runs on hundreds of GB of ram with up to 768 cpu cores.
To transfer files: right-click on file, pick Copy. Unplug mouse, plug mouse into other computer. Right-click, paste.
(Score: 2) by VLM on Tuesday June 06 2017, @03:59PM (1 child)
There are no obvious factual errors in Danny's reply to the best of my knowledge at this time.
A very short answer to your very specific question in a limited sense is "yes"
A longer answer to that specific question including plenty of low level implementation examples is at:
http://www.braveclojure.com/concurrency/ [braveclojure.com]
Clojure for the Brave and True is a bit of an acquired taste but I figured it would be more fun than a link into clojuredocs.org. clojuredocs is best used if you already know you want a future and you merely forgot some detail about futures.
Its not a magic or magic-ish language like Erlang you kinda have to intentionally parallelize stuff in Clojure for it to run multi-core but its not hard either and there's plenty of support.
It works.
(Score: 2) by DannyB on Tuesday June 06 2017, @04:39PM
This [objectcomputing.com] is an intro that I found useful as an into to Clojure, a long time ago.
I think I remember an amusing YouTube video where Rich Hickey mentions running some cool core.async program on Azul's custom hardware with hundreds of cpu cores.
I am excited to try Pixie Lisp on a Pi. So many projects to tinker with. So little time. Ugh.
To transfer files: right-click on file, pick Copy. Unplug mouse, plug mouse into other computer. Right-click, paste.
(Score: 2) by hendrikboom on Saturday June 10 2017, @01:22AM
I believe Gambit has a multicore implementation in beta testing -- including multicore garbage collection, But not garbage collection running in parallel with program execution.
Racket may well be working on something similar, but I don't remember the details.
-- hendrik