Purescript Advent Of Code Starter Kit

This is a Purescript starter kit for Advent of Code solutions.

Example of a repo that uses this starter kit.

Installation

Clone the repo and build

Clone the repo and build and run the CLI. This repo will use npm to install the latest purescript compiler and spago build tool in your local directory.

git clone https://github.com/fpindia/purescript-adventofcode
cd purescript-adventofcode
npm install
npx spago build
npx spago run

If this prints a brief help message then you are all set with the dev tools!

Getting the AdventOfCode cookie

This is needed if you want to be able to automatically download your puzzle input.

• First login to Advent of Code.
• Then with Firefox:
  • hit F12 in order to open the developer console
  • go to «Storage» tab, select «Cookies» in the left hand pane
  • Copy the «value» field of the «session» Cookie. On the screenshot, it's the part that starts with «536…»
• Or with Chrome:
  • Right-click, inspect, to open developer tools.
  • Go to «Network» tab, refresh the page to see all the network requests
  • In the left «name» pane, Click on the HTML request. click «Cookies» tab on the right page, and grab the value for «session» cookie.
• Copy the .env.template file into .env.
• Paste the cookie in the AOC_COOKIE variable. The .env file should look like this:

AOC_COOKIE="536…"
AOC_INPUT_DIRECTORY="input"

You are done ! You should now be able to download the input file by running the aoc command.

Editor setup

We recommend one of the following editor setups -

Spacemacs

Spacemacs is a user friendly emacs distribution with excellent inbuilt support for Purescript.

Enable the purescript layer by putting the following in your $HOME/.spacemacs file, in the dotspacemacs-configuration-layers section -

  (purescript :variables
     node-add-modules-path t
     psc-ide-use-npm-bin t
     )

Restart spacemacs with <space>-q-R.

Then open src/Main.purs in the editor, and run <space>-m-m-s to run the purescript ide server.

VSCode

VSCode is a lightweight editor/ide from microsoft.

Install the purescript-ide plugin by Nicholas Wolverson.

Then open src/Main.purs in the editor.

Usage

aoc boostrap YEAR DAY

Use aoc bootstrap to immediately start coding for a given day. It downloads the input file, creates a sample module for that day.

Example - To bootstrap the solution for the 5th puzzle in 2020, run ./aoc bootstrap 2020 5

It will create the following files -``

purescript-adventofcode
├── input
│   └── 2020
│       └── 05
└── src
    └── Year2020
        └── Day05.purs

The src/Year2020/Day05.purs is simple but it contains all you need: 2 methods, part1 and part2, that take as parameter the content of the input file, and return the expected value.

module Year2020.Day05 where
...

--------------------------------------------------------------------------------
-- Write your solutions here

part1 :: String -> Effect Unit
part1 input = do
  let result = "<TODO>"
  log $ "Part 1 ==> " <> result

part2 :: String -> Effect Unit
part2 = do
  let result = "<TODO>"
  log $ "Part 2 ==> " <> result

...

aoc run YEAR DAY

Use aoc run to quickly run your current solution and measure the execution time.

./aoc run 2020 5
Part 1 ==> ...
Obtained in: 0.296ms

Part 2 ==> ...
Obtained in: 0.3i9ms

You can also run only a specific part with the --part flag.

./aoc run 2020 5 --part1
Part 1 ==> ...
Obtained in: 0.297ms

aoc download YEAR DAY

Use aoc download to quickly download your puzzle input and put it in the correct location.

./aoc download 2020 5

This will download the input into a file called inputs/year2020/day5.

Helper functions available

This project includes the following libraries -

1. Bignumber. For dealing with arbitrarily large integers that don't fit in 64 bits.
2. Parsing. Parsec style parsing for Purescript.
3. Free. Useful to build interpreters and automatons.

Also included are a bunch of helper functions in AOC.Lib.

Utilities

• iterate :: forall a. Int -> (a -> a) -> a -> a

  Apply a function repeatedly a specified number of times

• pipeline :: forall a. a -> Array (a -> a) -> a

  Successively run an array of functions on a value

• eitherToMaybe :: forall e a. Either e a -> Maybe a

  Convert an either into a maybe

Bignumber

• intToBigNumber :: Int -> BigNumber

  Convert an integer into a bignumber

Array Utilities

• spanMap :: forall a b. (a -> Maybe b) -> Array a -> {init :: Array b, rest :: Array a}

  Split an array into two parts: 1. the longest initial subarray for which all elements return a Just value for the supplied function, and returns the values mapped to the Just values 2. the remaining elements

Text splitting

• splitFirst :: Pattern -> String -> Maybe {left::String, right::String}

  Split by a pattern once and return left and right params To make multiple splits, use Data.String.split

• chunk :: Int -> String -> Array String

  Split a string into chunks of fixed length

Getting the input

NOTE: Normally you won't need to use the below functions, since the input is automatically passed to the part1 and part2 functions.

• inputFileLocation :: Int -> Int -> String

  The location of the input file

• readInput :: Int -> Int -> Effect String

  Read the entire input file into a single string

Parsing

• preventNaN :: Number -> Maybe Number

  Turn NaN's into Nothing

• parseIntBaseN :: Int -> String -> Maybe Int

  Parse an integer in specified base

• parseInt10 :: String -> Maybe Int

  Parse an integer

• parseFloat :: String -> Maybe Number

  Parse a float