Lytlang

Lytlang's goal is to enable you to write Elixir code more tersely and is itself written in Elixir. Its syntax is a terrible merging of Elm, CoffeeScript, Elixir, a sprinkling of Rust, and some made-up crap. Here's a rough preview:

!mod Leetcode

# Look, a comment!

### part of the comment
Look, a multiline comment!
part of the comment ###

@doc
	LeetCode #1: two_sum

	TODO: store a map of complements (differences) as iterating for O(n)

fn two_sum _:list _:int i=0 ::
	[] _ _ -> nil
	[cur | rest] target current_index
		Enum.find_index rest, fn x -> cur + x == target ::
			nil -> two_sum rest target current_index
			i -> [current_index, 1 + current_index + i]

@doc LeetCode #2: add_two_numbers

fn add_two_numbers _:list _:list _=[] i=0 ::
	[] _ l m, _ [] l m -> finish_add_two_numbers l m
	[n1 | r1] [n2 | r2] l carry
		add_two_numbers r1 r2 [rem (carry + n1 + n2) 10) | l] (div n1 + n2 10)

fn finish_add_two_numbers l:list m:int -> m == 0 ? l : [m | l]

@doc
	LeetCode #3: longest non-repeating susbtring

	TODO: better utility function names?

fn longest_non_repeating_substring s
	s |> String.codepoints |> Enum.reduce {0 0 0 %{}} &ln3_reducer/2 |> elem 0

fn ln3_new_least least map char
	Map.has_key? map char ::
		true -> max least ((Map.get map char) + 1)
		_ -> least

fn ln3_reducer char {mx i least map}
	least = ln3_new_least least map char
	{(max mx (i - least + 1) (i + 1) least (Map.put map char i)}

@doc
	LeetCode #4: median of sorted arrays

	TODO: solution should me O(log(m+n))
	TODO: finish an actual solution?

fn median_of_sorted_arrays _ _ -> 3

@doc LeetCode #65: Valid Number

@valid_decimal_number_regex ~r/^\s*(?:\+|-)?\d+(?:\.(?=\d))?\d*(?:e(?=[\d\+-]))?(?:\+|-)?\d*(?:\.(?=\d))?\s*$/

fn valid_decimal_number s -> Regex.match? @valid_decimal_number_regex s

TODO: Add more description

NOTE: This doesn't work at all. I'm still figuring out how to even go about creating an AST and converting that into valid Elixir code. This will probably never happen.

Development Resources

• https://pl-rants.net/posts/leex-yecc-in-elixir/
• https://notes.eellson.com/2017/01/22/html-parsing-in-elixir-with-leex-and-yecc/