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Emerald

Installation

The language requires Ruby installed and can be downloaded from https://www.ruby-lang.org/en/
(developed in version 2.5)

To run in the terminal: -d flag for debug mode

ruby rules.rb file [-d]

Data types

  • Boolean - true & false
  • Number - This type represents both integers and floating point numbers (1 & 2.5) dot is used as a decimal point. You can also represent numbers with arithmetic expressions (1/3)
  • Text - "Hello" alternatively 'world' (" or '), but not a mix of the two
  • List - [3, 4, "text", true] can contain a mixture of all data types, every index is an integer.

Operations

  • Addition (number) +
  • Subtraction (number) -
  • Multiplication (number) *
  • Division (number) /
  • Concatenation (text) +

Comparisons

  • == (equal to)
  • >= (equal or greater than)
  • <= (equal or less than)
  • > (greater than)
  • < (less than)
  • != (not equal to)

Output

  • Print - $stdout
  • Warn - $stdout (warning label)

Control flow

  • Function - with parameters (return not implemented, but part of design specification)
  • Variable - name may not start with number or underscore
  • If-block - elseif & else
  • For-loop - integer, without index
  • While-loop - (break not implemented, but part of design specification)

Syntax

The syntax is independent of whitespace and newline & uses keywords to mark the beginning and end of flow and declarations

Comments

# Comments begin with a hash and ends at newline
# There is not syntax for multi-line comments

Data types

# Boolean
true
false

# Number
1
2.5
1+2-3*1/3

# Text
"Hello, world!"
'Never gonna give you up'

# List
[3, 2.5, "text", true]

Operations

# Addition
1 + 2 # => 3

# Subtraction
4 - 3 # => 1

# Multiplication
4 * 2 # => 8

# Division
9/3 # => 3

# Concatenation
"Hello " + "there" # => "Hello there"
"Number " + 42 # => "Number 42"

Comparisons

# Equal to
2 == 1 # => false

# Equal or greater than
2 >= 1 # => true

# Equal or less than
2 <= 1 # => false

# Greater than
2 > 1 # => true

# Less than
2 < 1 # => false

# Not equal to
2 != 1 # => true

Output

# Print
print("Hello world") # => Hello world

# Warn
warn("Heads up!") # => [WARNING] Heads up!

Control flow

# Function
function print3(parameter) # declaration
	print(parameter)
	print(parameter)
	print(parameter)
end function

print3("Go!") # call

# Variable
variable_name = 13.37 # assignment
variable_name # reading

# If-block
if false then
	# an if-statement must have one if-block
elseif true then
	# an if-statement can have several (or no) elseif-blocks
else
	# an if-statement can have one else-block
end if

# For loop
for 10 do
	# a for loop requires one integer
end for

# While loop
index = 1
while index < 10 do
	index = index + 1
end while