Yang first syntax idea

test.ts

from "std/collections" import {List};
from "std/os" import {File};

export enum Result<SuccessType, ErrorType> {
	Success(SuccessType),
	Error(ErrorType),
}

export enum Maybe<T> {
	Some(T),
	None,
}

export function main(): uint8 {
	const input_file_name = "./input.txt";

	match File.read_file(input_file_name, encoding: "utf-8", as: string) {
		Result::Success(file_contents) => {
			const trimmed_file_contents = file_contents.trim();
			const chars = trimmed_file_contents.chars();
			const mapped_chars = List.map(chars, match {
				'(' => +1,
				')' => -1,
				_ => 0
			});

			const last_floor = get_last_floor(mapped_chars);

			Logger.info(`Santas last floor is: $last_floor`);

			return 0;
		},
		Result::Error(reason) => {
			Logger.error(`Could not read "$input_file_name": $reason`);

			return 1;
		}
	}
}

function get_last_floor(levels) => List.sum(levels);

function get_basement_index(levels): Maybe<usize> =>
			levels
			|> List.reduce(Tuple(Maybe::None, 0), function(accumulator: Tuple<Maybe<usize>, int32>, entry: int32, index: usize): Tuple<Maybe<usize>, int32> {
				match accumulator {
					Tuple(Maybe::Some(_found_position), _current_level) => accumulator
					Tuple(Maybe::None, current_level) => {
						return match current_level + entry {
							-1 => Tuple(Maybe::Some(index), -1),
							new_level => Tuple(Maybe::None, new_level),
						};
					}
				}
			})
			|> then(& &.0);