Earl Grey (website) is a new language that compiles to JavaScript (ES6). Here's a quick rundown of its amazing features:
- Python-like syntax
- Fully compatible with the node.js ecosystem
- Generators and async/await (no callback hell!)
- Powerful, deeply integrated pattern matching
- Used for assignment, function declaration, looping, exceptions...
- A DOM-building DSL with customizable behavior
- A very powerful hygienic macro system!
- Define your own control structures or DSLs
- Macros integrate seamlessly with the language
- Macro libraries! Test with earl-mocha, build with earl-gulp, make dynamic pages with earl-react, etc.
- And much more!
Counting all words in a block of test. Note that count-words is a variable name, not a subtraction (it is equivalent to the name countWords, if that's the notation you prefer).
count-words(text) = counts = new Map() words = text.split(R"\W+") words each word -> current-count = counts.get(word) or 0 counts.set(word, current-count + 1) consume(counts.entries()).sort(compare) where compare({w1, c1}, {w2, c2}) = c2 - c1 {x, y, ...} is the notation for arrays in Earl Grey. Objects are denoted {field = value, field2 = value2, ...}
Generators: the following defines a generator for the Fibonacci sequence and then prints all the even Fibonacci numbers less than 100. It shows off a little bit of everything:
gen fib() = var {a, b} = {0, 1} while true: yield a {a, b} = {b, a + b} fib() each > 100 -> break n when n mod 2 == 0 -> print n The each operator accepts multiple clauses, which makes it especially easy to work on heterogenous arrays.
Asynchronous: EG has async and await keywords to facilitate asynchronous programming, all based on Promises. Existing callback-based functionality can be converted to Promises using promisify:
require: request g = promisify(request.get) async getXKCD(n = "") = response = await g('http://xkcd.com/{n}/info.0.json') JSON.parse(response.body) async: requests = await all 1..10 each i -> getXKCD(i) requests each req -> print req.alt Classes:
class Person: constructor(name, age) = @name = name @age = age advance-inexorably-towards-death(n > 0 = 1) = @age += n say-name() = print 'Hello! My name is {@name}!' alice = Person("alice", 25) Pattern matching acts like a better switch or case statement. It can match values, types, extract values from arrays or objects, etc.
match thing: 0 -> print "The thing is zero" < 0 -> print "The thing is negative" R"hello (.*)"? x -> ;; note: R"..." is a regular expression print 'The thing is saying hello' Number? x or String? x -> print "The thing is a number or a string" {x, y, z} -> print 'The thing is an array of three things, {x}, {y} and {z}' {=> name} -> print 'The thing has a "name" field' else -> print "I don't know what the thing is!"