Move.js
movelang.org
movelang.org
When compared to JavaScript, Move has the following key features:
- Simpler. E.g. there's only one way to declare functions, no need for var declarations, only a single type of equality operators and no need for terminating statements with semicolons.
- Less boiler-plate code needed. Move introduces a few carefully selected features like the "import" and "export" keywords, and @-shorthand for this access.
- Move runs in any >=ES3 JavaScript runtime and thus can be used as a universal programming language for everything from running in web browsers to powering complex offline systems.
Also, interestingly, it's from the guy behind Kod and Spotify's design.
hello = ^{ "Hello " + name }
function hello(name) do
"Hello " + nameIf they wanted "smaller" lambdas, why not use e.g. C#'s syntax? Or Scala's?
Also, implicit scoping => yet an other broken language. Not worth looking at.
What other solution do you propose? Demanding all variables are declared? That's a very good idea, but it goes against the spirit of javascript and other dynamic languages.
After extensive experience with it in Python and Ruby, I don't. It's just too prone to typos and broken scoping to be worth it.
> What other solution do you propose? Demanding all variables are declared?
yes.
> That's a very good idea, but it goes against the spirit of javascript and other dynamic languages.
No it does not.
* Javascript has explicit scoping, it's mandatory in strict mode (ES5) and extensions add even more flexible scoping methods (e.g. `let` in Mozilla's JS 1.7[0])
* Likewise with Perl under `use strict`
* Or even in VB and VBScript using Option Explicit
* Smalltalk mandates declaring local variables
* Scheme (and more generally lisps) make extensive use of `let`-type blocks
Dynamic typing and implicit scoping are entirely orthogonal, and I truly find no value whatsoever in implicit scoping: it's a hindrance in every situation, and it helps in none.
[0] https://developer.mozilla.org/en/New_in_javascript_1.7#Block...
> It's just too prone to typos and broken scoping to be worth it.
Predeclared variables are just as prone to typos, which will also break your code -- and just as prone to broken scoping. By accidentally shadowing an external variable you make it unreachable for the remainder of the current function, and all nested functions within.
Clearly, declaring the type of a variable is not necessary in a dynamic language, so the only purpose of a variable declaration is to manually mark it's scope, shadowing any potential name conflict.
There are no situations where shadowing a variable is desirable. It's always best to be able to reach any variable that exists in the current lexical scope, should you find the need.
The only ambiguous situation in which you'd want to use a "var" on purpose is to explicitly shadow an external variable of the same name -- if you accept that shadowing is undesirable, and choosing a more descriptive name for the inner variable is preferable, then QED.
Dynamic languages should not have variable declarations.
Not so: declaring variable name & scope ensures immunity to the "I wanted to change this variable, but I'm creating a new one instead", and this can be checked statically even in dynamically typed languages.
> There are no situations where shadowing a variable is desirable.
While I do not agree with this assertion, I can see where you come from and explicit scoping is still superior to implicit for this: if there are no situation where shadowing is desirable, you can make the language statically forbid shadowing. There, done.
> It's always best to be able to reach any variable that exists in the current lexical scope, should you find the need.
It is not, however, desirable to reach and unknowingly alter an existing variable in an ancestral lexical scope when you did not mean to and just happened to pick an existing name in a callback 2-levels down the stack. The result of this is silent corruption of program state, and it is a risk in any implicitly-declared scoping system with mutable bindings.
> The only ambiguous situation in which you'd want to use a "var" on purpose is to explicitly shadow an external variable of the same name -- if you accept that shadowing is undesirable, and choosing a more descriptive name for the inner variable is preferable, then QED.
Then QED nothing, since as I pointed out it is perfectly possible to make variable shadowing statically illegal, ensuring that no variable is hidden and no variable is silently reused or replaced either.
> Dynamic languages should not have variable declarations.
Nope.
Furthermore, explicit scoping significantly increases readability and lowers cognitive burden: readers don't have to wonder whether a given assignment is local to the current lexical scope, it's spelled out for them. And if it's a bare assignment (not a new variable), explicit scoping makes it easier to find out where the variable is first used. Not to mention it allows the language to protect against in-scope reuse (in cases of debatable-quality imperative code with scopes more than a screenful long), as the second declaration may (and generally will) be statically marked as the redeclaration of an existing variable, and will be refused by the language's runtime.
And all of that for the cost, in most languages, of 3 characters. Almost nothing. All the issues you mentioned (since you didn't mention typing) are not issues of explicit scoping but with specific implementations thereof.
You declared a variable once and use it n times. If you accidentally shadow a variable, via typo, then you only have one place to check for the typo. The compiler/interpreter will complain if you don't happen to also consistently made that typo everywhere you use the variable.
In language with implicit declaration, everywhere you use the variable is as likely to have typo that the compiler/interpreter cannot check for you.
1 place to check vs. n places, is a no-brainer which one is more error prone.
> By accidentally shadowing an external variable ...
In language with explicit declaration you have to accidentally declare same name AND use it with that accidental name. If both doesn't happen, the interpreter will complain.
In language with implicit declaration, one accidental typo is all it takes to accidentally shadow a variable.
You have just made a case against implicit declaration.
> There are no situations where shadowing a variable is desirable. [...] if you accept that shadowing is undesirable, and choosing a more descriptive name for the inner variable is preferable
So, to name a local variable "list", you have to look up on every outer variables involved to make sure nowhere else also use the name "list".
And let's give up on naming an outer variable name "list" because, who knows where some inner function might decide to use such name for local variable.
> choosing a "more descriptive name" for the inner variable
More like "more redundant name". Implementing "date_diff" function? Forget naming different of it "delta", let's name it "date_diff_delta", or else it might conflict with some outer variable name.
Congratulation, you have successfully remove concept of namespace from your language.
> if you accept that shadowing is undesirable
Then you should consider other job than programming.
int (^aBlock)(int) = ^(int a) {
return a;
};Whether to write:
hello = lambda (name) { "Hello " + name }
hello = ^ (name) { "Hello " + name }
hello = function (name) { "Hello " + name }
is just a color of the bike shed decision.
hello = \name -> putStrLn ("Hello, " + name)
You might say that significant whitespace (i.e. the indentation level signifies structure) is a more natural way, but when you think about it there's no where else in these peoples lives where indentation of text determines it's function or effect. When you e.g. in Word indent text it's a purely visual effect (which might imply or give greater meaning to structure, but not define it). Thus, significant whitespace is not as natural as parenthesis and -- it turns out -- curly braces.
Now, I only did qualitative research and have yet to see a large uptake in usage. I personally use Move for 95% of everything I write nowadays and I have colleagues and friends who are also writing things in Move, so I guess time will tell if this is actually a more "natural" programming language than, say, JavaScript.
I recently wrote this update on the Move language. A sort of retrospect: http://rsms.me/2011/07/30/an-update-on-move.html
Programming should change the way you think. The language is an artifact that you program through, but that's not the critical problem in conceiving of and executing good software design.
A cursory examination of the Move site does not make it look more attractive than other Javascript based languages, and the explanations it offers i don't think would make it more accessible to non-programmers either.
What gives? /me is confused.
The prototypal inheritance example in that post does not read in an intuitive manner, and certainly don't improve the clarity of meaning for prototypal inheritance (especially now that it's using the word "class").
The only compelling thing i can find in here so far is that it's trying to provide common functionality from ES5. But again, i don't see what that has to do with building a language that is easy for non-programmers to grok, making the Javascript semantic model more accessible, or even making JS coding more readable.
It doesn't have to be Coffeescript vs Move or Move vs anything. I don't think that rsms achieves what his site seems to set out to do, although i agree that a common ES5 behavioral platform is a good thing.
His opinion of CoffeeScript is interesting, and provides some insight into his motivation, i guess, but i think i may have introduced a red-herring into the conversation.
* ^ replacing function
* default values for arguments, ^(x: 4){...}
* print instead of console.log
* array slicing x[1:3], x[:-2]
* embedded HTML, div = <div/>
Edit: like beaumartinez says, the Github page explains the differences much better than the site: https://github.com/rsms/move
Overall, seems very half-assed, a few cosmetic changes (half of them making the language worse instead of better) and that's about it.
For example, no need for var declarations. Well, wait a minute, how do I as an engineer scope a variable then? In javascript, scope is determined by functions when using a var and is global otherwise. Are all variables global? Or are they just in a namespace? Or are they all scoped as if they had var in front? Things like this will trip me up all the time and I will always have to refer to documentation.
For designers, mostly they don't want to work with functions and variables anyway, how big of a benefit is it that they don't need a var and there is only one way to declare a function? Learning this language seems like it would take the same amount of overhead as learning identical features in javascript. Why not just learn a subset of javascript instead?
I think writing LOGO in the browser with something similar would be cool.
http://en.wikipedia.org/wiki/Logo_(programming_language)
FORWARD 100
LEFT 90
FORWARD 100
LEFT 90
...
a = []; a[10] = undefined; a["x"] = "foo"The right associativity of function application is a very peculiar feature and it turns my Haskell brain upside down.
edit: wait, its functions are not curried, so I'm not sure it's right-associative, it just looks that way if you've read haskell code in the past: positional arguments are still tuples (comma-separated)
If this code was haskell and you translated it to Move it would look like this: `print foo.makeHello, capitalize, name`