This article documents several important additions to Ruby Syntax.

1) Block parameters

Option A: Providing a name yourself

a = [ "a", "b", "c" ]
a.each { |x| puts x }

Option B: Use the numbered parameters

a = [ "a", "b", "c" ]
a.each { puts _1 }

Option C: Use "it"

a = [ "a", "b", "c" ]
a.each { puts it }

2) Infinite Ranges

Range up until:

a = [ "a", "b", "c", "d", "e", "f" ]
puts a[...-2].to_s

> ["a", "b", "c", "d"]

a = [ "a", "b", "c", "d", "e", "f" ]
puts a[..-2].to_s

> ["a", "b", "c", "d", "e"]

Range starts from:

a = [ "a", "b", "c", "d", "e", "f" ]
puts a[3..].to_s

> ["d", "e", "f"]

a = [ "a", "b", "c", "d", "e", "f" ]
puts a[0..].to_s

> ["a", "b", "c", "d", "e", "f"]

Other use cases:

# Example 1: Rails Active Record

Invoice.where(paid: false).where(expires_at: ..Time.current)

# Example 2: Get a substring

str = "Hello World"
puts str[..5]

> "Hello "

3) Hash shorthand

Ruby automatically assigns the value of a local variable to the hash key if the name matches.

name = "John"
age = 30
x = { name:, age: }
y = { name: name, age: age }
puts x == y

> true

4) Arguments Forwarding

Arguments can be forwarded by using triple dots.

def plus(a, b)
  a + b
end

def plus_with_comment(comment, ...)
  puts comment
  puts plus(...)
end

plus_with_comment("Adding 1 and 2", 1, 2)

> Adding 1 and 2
> 3

5) Endless Method Definition

Ruby allows endless method definition.

# Normal, with end
def plus(a, b)
  a + b
end

# Endless
def minus(a, b) = a - b

puts plus(1, 2)
puts minus(1, 2)

> 3
> -1