darioncassel / kale

Kale, a lisp-like language

Kale, a lisp-like language.

About

This project is an experiment in creating a programming language without knowing any of the theory involved. I essentially wanted to see where tabula rasa would take me before I took any PL classes.

Interesting things about Kale

• Uses postfix notation: (1 2 +) # => 3 #
  • Removed to facilitate easier disambiguation. Wasn't really a feature to begin with.
• Is entirely stack-based.
• Is only lisp-like because of the parenthesis; it doesn't actually use s-expressions.
• Is interpreted to some kind of custom bytecode and then run on a very very simple VM (the kvm?).
• Only supports integer input, but can output floats.

What it does so far

• Simple output:

# Say hi! #
(say hello!)
# => hello! #

• Comments (multiline):

# this is a multi
    line comment! #
(say (+ 1 2)) 
# => 3 #

Caveat: Comments must have an end #

• Calculator-like behavior

(say (/ (* (+ 1 2) 3) 2))
# => 4.5 #

• Variable definition

# Allocate a new variable, a #
(var a)
# Print out what a contains #
(say (val a))
# => None #

• Variable assignment

# Allocate a new variable, a #
(var a)
# Set a to 3 #
(set a 3)
# Print out a #
(say (val a))
# => 3 #

• Using variables in expressions

(var a)
(set a 1)
(var b)
(set b 2)
(say (+ (val a) (val b)))
# => 3 #

• Conditonal Operators

(set a 1)
(set b 2)
(say (> a b)) # => False #
(say (>= a b)) # => False #
(say (< a b)) # => True #
(say (<= a b)) # => True #
(say (== a b)) # => False #

Requirements

• Python 3

How to run:

python3 src/kale.py test.kl