The RatLang Programming Language

Hello World

rat> \"Hello World!"
Hello World!

Print anything by putting a backslash in front.

Basic arithmetic

rat> 3.0/20.0
0.15

Simple math works like you’d expect. This can be simplified to:

rat> 3./20.
0.15

And simplified even more to:

rat> 03/20
0.15

Implicit decimal point

One of the biggest differences between RatLang and other languages is the implicit decimal point. If you type a natural number without a decimal point like 35, it will be treated as 0.35 instead. This lets you write percentages easier:

rat> 3.50*80*70*1.08
2.11680

Alternate operators

Since parentheses are hard and clumsy to type, a second set of arithmetic operators with higher precedence has been introduced in addition to the regular operators.

rat> 3p4/1p6      # Equivalent to (0.3*0.4)/(0.1*0.6)
2.0
rat> 3s41*2s1     # Equivalent to (0.3 + 0.41) * (0.2 + 0.1)
0.213

The two lines of code above should be read as .3 product .4, divided by .1 product .6 and .3 sum .41, multiplied by .2 sum .1.

Operator precedence is defined as follows:

Parentheses can be used to group expressions and override this order of operations. However, you will find that parentheses are rarely necessary in RatLang, as you get more comfortable with the alternate operators.

Variables

rat> lA = 4       # "Let" A equal 0.4
0.4
rat> \A
0.4

Variable names consist of one or more uppercase letters or underscores. Lowercase letters are not allowed in variable names since they're used as operators.

Functions

rat> lA = f(X){X + 3}
(function value)
rat> \A(3)
0.6

The f operator is used to define lambda expressions. Functions in RatLang are purely functional and can have no side effects. They consist of an argument list and a return expression, which can be another function. All functions are anonymous and can be assigned to variables like normal values.