Funco

This is a small functional programming language I wrote for fun inspired by lispy and Atto.

Still, it has a lexer and a parser, and some optimizations (like recursive tail calls, although they need to be tagged).

The only requirement is Python 3.10 or later.

There are lots of limitations, but check TODO for some ideas to contribute.

The language

An example:

# example of a factorial function
def fact(n acc)
    if =(n 1)
        acc
    else
        # tagging a tail call with "@" so it can be optimized
        @fact(-(n 1) *(acc n))
    end
end

# main is the entry point of a program
def main()
    display("Running fact(50)...")
    display(fact(50. 1))
end

# output:
# Running fact(50)...
# 3.0414093201713376e+64

A program can have:

line comments, with #
function definitions
expressions

A main() function is required and will be executed as entry point for the program.

Function definition:

def ident([param1 [param2] [...]])
    [...]
end

Expressions can be:

function calls
conditionals with if [elif [elif] [...]] [else]
literals

Literals include:

numbers (int or float): 1, 1.5
strings: "this is a string"
booleans (true or false), as result of some logical functions; although 0 is false and non-zero is true
lists
functions
none for "no value"

Operators are functions, that includes:

+, -, *, /, mod
>, <, >=, <=, =, !=
and, or, not

For example, adding two numbers:

+(1 1) # should be 2

Other built-in functions are:

int(value): convert a value into a integer
float(value): convert a value into a float
string(value): convert a value into a string
list(a b c d): convert its arguments into a list, for example list(1 2 3 4)
int?(value): returns true if a value is a integer
float?(value): returns true if a value is a float
string?(value): returns true if a value is a string
list?(value): returns true if a values is a list
none?(value): returns true if a value is none
boolean?(value): returns true if a value is a boolean
function?(value): returns true if a value is a function
head(list): returns the first element of a list
tail(list): returns the end of a list excluding the first element
empty?(list): returns true if a list is empty
size(list): returns the size of a list
min(list): returns the smaller value in a list
max(list): returns the larger value in a list
contains(value list): returns true if a list contains a value
map(fn list): applies a list to a function
filter(fn list): applies a list to a function, excluding the items for which the function returns true
fold(initial fn list): folds using a function the receives the accumulator and the value, and returns the updated accumulator
take(n list): return the first n elements of a list
drop(n list): return the list dropping the n first elements
display(value): prints its arguments to the screen, for example display("hello" "world")
..(i j): generate a list of integers from i to j

See the examples in ./examples.

Licence

This project is licensed GPL 3.0.