willowell

///! Version: C++17

#include <algorithm> // for std::reverse()
#include <cstdint> // int64_t
#include <filesystem> // std::filesystem::path
#include <fstream> // std::ifstream, std::ofstream
#include <iostream> // the usual console I/O stuff
#include <sstream> // istringstream for parsing a string, see split() below
#include <string> // std::getline(), std::stol()
#include <vector>

willowell

// Try it out on https://godbolt.org/ with Clang with concepts!

// GitHub insists on this having a tab size of 8 even though I told it to use 4, even after deleting and reuploading this. :-(
// Please excuse the massive indents!

#include <iostream>
#include <type_traits>

namespace MyProject {
	template <typename T>

willowell

// Requires at least C++17
#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>

int main() {
	
	// Path is relative to executable.
    std::filesystem::path filePath = "./out.txt";

willowell

The Haskell functions I am trying to translate:

promptLine :: String -> IO String
promptLine msg = do
    putStr msg
    hFlush stdout
    getLine

input :: Read a => String -> (a -> Bool) -> IO a
input msg validator = do

willowell

// for instance, this TS function

import fetch from "node-fetch";

const getData = async (url: string): Promise<any | null> => {
  try {
    const response = await fetch(url);
    const json = await response.json();
    return json;
  } catch (error) {