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RedScript Spec Sheet

If you have suggestions on different syntax, please create an issue: here.


Variables

RedScript has one kind of variable and does not need to be declared. However they have the same scoping rules as JavaScript's let.

result = 10 + 5
result = result + 5
# IO.inspect(result)
# 15

Compiled JavaScript:

let result = 10 + 5
result = result + 5
// IO.inspect(result)
// 15

Comments

RedScript has one kind of comment, a single line. All text is ignored to the right of the #.

# this is a single line comment
# commented_out_func()

String

RedScript has one kind of string, a double quote. Single quotes will not compile.
Strings can be interpolated with the #{} construct.

name = "Jane"
"Hello #{name}"

Compiles to JavaScript:

let name = "Jane"
`Hello ${name}`

Number

Number is the same as the JavaScript implementation.

typeof 1 == "number"
typeof 1.4 == "number"

Symbol

Symbol is the same as the ES6 JavaScript implementation with a syntax similar to Elixir/Ruby.

env = :prod

typeof :prod == "symbol"
# >> true
typeof env == "symbol"
# >> true

# use a symbol with a map (string keys are standard)
res = {foo: 1, [:bar]: 2}

Compiles to JavaScript:

let env = Symbol.for(":prod")

typeof Symbol.for(":prod") == "symbol"
typeof env == "symbol"

// use a symbol with a map (string keys are standard)
let res = {foo: 1, [Symbol.for(":bar")]: 2}

Boolean

Booleans are the same as JavaScript and many other languages.

true
false

Null

Null is the same as the JavaScript implementation.

null

Undefined

Undefined is the same as the JavaScript implementation.

undefined

Basic Arithmetic

Arithmetic is the same as the JavaScript implementation.

1 + 2
# 3
5 * 5
# 25
10 / 2
# 5

Anonymous functions

Anonymous functions have the same scoping rules as JavaScript but the syntax has a skinny arrow instead of a fat arrow.

double_num = (x) -> x * 2
let double_num = (x) => x * 2

Maps

RedScript does not not have an "Object" type like JavaScript. It has a "Map" type that acts like an immutable JavaScript literal. To make a change you must copy the object and merge in the new key/values.

You can copy maps in several ways. However Map.put and the literal notation are the most frequently used. Map.put is ideal for changing a map inside a pipeline. Both of these are similar to using ES6 spread syntax in JavaScript.

If you have to mutate a map for performance reasons you have to explicitly call Map.mutate

trying to mutate JS style will throw an error

map.bar = 4
# or
map["bar"] = 4

Error: you can't mutate Maps
Perhaps you want to try using:
  map_copy = {old_map <- bar: 4}
or
  map_copy = Map.put(old_map, "bar", 4)

In order to change a value of a map you must use Map.put or the shorthand notation.

map = {foo: 1, bar: 2}
map = Map.put(map, "bar", 4)
IO.inspect(map)
#log {foo: 1, bar: 4}

# or literal notation
map = {map <- foo: 2}
IO.inspect(map)
#log {foo: 2, bar: 4}

Compiled JavaScript

map = {foo: 1, bar: 2}
map = Map.put(map, "bar", 4)
IO.inspect(map)
//log {foo: 1, bar: 4}

// or literal notation
map = {...map, foo: 2}
IO.inspect(map)
//log {foo: 2, bar: 4}

If Else Uness

RedScript borrows the same sytax from Elixir for if, else, and unless

if foo > 2 do
  # do work
end

if foo > 2 do
  # do work
else if foo > 2
  # do work
else
  # do work
end

unless foo > 2 do
  # do work
end

Compiled JavaScript

if (foo > 2) {
  // do work
}

if (foo > 2) {
  // do work  
} else if (foo > 2) {
  // do work  
} else {
  // do work
}

if (!(foo > 2)) {
 // do work
}