fresh

Fresh Programming Language

A custom lisp dialect intepreter
First written in Python, and being rewritten in Haskell
Example Fibonacci indexer:

(function fibr [count current old]  
    (if (< count 2)  
        current  
        (fibr (- count 1) (+ current old) current)  
    )  
)  
(function fib [index]  
    (fibr index 1 0)  
)  
(function main []
    (fib 4)
)  
5  

To Run

cd python  
./bin/repl.py  

Features

Supports Booleans

• true and false
• (not true) false - negate given boolean
• (and false true true) false - "and" any number of booleans together
• (or false true true) true - "or" any number of booleans together

Supports Integers

• (+ 4 3 3) 10 - add any number of ints
• (- 5 1 1) 3 - subtract any number of ints from the first int
• (* 2 2 2) 8 - multiply any number of ints
• (= 2 2 3) false - return true if any number of ints are equal
• (> 5 4 3) true - return true if any number of ints are in descending order
• (< 4 3 4) false - return true if any number of ints are in ascending order

Supports Conditional Branching

• (if true 4 0) 4 - branch based on condition

Supports variable assignment

• (define a 4) (function main [] (+ a 1)) 5 - define a mapping in the environment for later reference

Supports lambdas

• (function main [] (lambda [num] (+ num 1))) - returns a lambda that will add one to it's single argument when called
• (define square (lambda [i] (* i i)))(function main [] (square 5)) 25 - assign a lambda to a variable to reference later

Supports structs and member access

• (struct x y) - returns a struct node that has members "x" and "y"
• (define person (struct height weight))(define quinten (person 178 77))(function main [] quinten) - returns a struct instantiation of a "person" with members "height" and "weight"
• (define person (struct height weight))(define quinten (person 178 77))(function main [] (member quinten height)) - returns the "person" "quinten"s "height" which is 178

Todo

• Implement type checker
• Add methods to structs to support classes