day 1

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

.envrc

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+use flake

day01.hs

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+{-# LANGUAGE OverloadedStrings #-}
+
+import Data.Char (digitToInt, isDigit)
+import Data.Text qualified as T
+import Lib (readFile')
+
+first :: T.Text -> Int
+first s = f * 10 + l
+  where
+    values = T.filter isDigit s
+    f = (digitToInt . T.head) values
+    l = (digitToInt . T.last) values
+
+second' :: T.Text -> [Int]
+second' s
+  | T.null s = []
+  | T.isPrefixOf "one" s = 1 : second' (T.tail s)
+  | T.isPrefixOf "two" s = 2 : second' (T.tail s)
+  | T.isPrefixOf "three" s = 3 : second' (T.tail s)
+  | T.isPrefixOf "four" s = 4 : second' (T.tail s)
+  | T.isPrefixOf "five" s = 5 : second' (T.tail s)
+  | T.isPrefixOf "six" s = 6 : second' (T.tail s)
+  | T.isPrefixOf "seven" s = 7 : second' (T.tail s)
+  | T.isPrefixOf "eight" s = 8 : second' (T.tail s)
+  | T.isPrefixOf "nine" s = 9 : second' (T.tail s)
+  | isDigit (T.head s) = digitToInt (T.head s) : second' (T.tail s)
+  | otherwise = second' (T.tail s)
+
+second :: T.Text -> Int
+second s = head values * 10 + last values
+  where
+    values = second' s
+
+main :: IO ()
+main = do
+  input <- T.lines <$> readFile' "day01.in"
+  putStr "Q1: "
+  print . sum . map first $ input
+  putStr "Q2: "
+  print . sum . map second $ input

flake.lock

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+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1701445246,
+        "narHash": "sha256-SNnOV9h/rSZFuF/PZDbHRjgtOzPiP8jSKzN3oWT8Clg=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "9415b539cd02e4eb3446fd0ccaa405d110eff173",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "release-23.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "utils": "utils"
+      }
+    },
+    "utils": {
+      "locked": {
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "AoC 2023 in Haskell";
+
+  inputs = {
+    nixpkgs.url = github:nixos/nixpkgs/release-23.11;
+    utils.url = github:numtide/flake-utils;
+  };
+
+  outputs = { self, nixpkgs, utils }:
+    utils.lib.eachDefaultSystem
+      (system:
+        let
+          pkgs = import nixpkgs {
+            inherit system;
+          };
+          src = ./.;
+        in
+        with pkgs; {
+          devShells.default = mkShell {
+            buildInputs = [
+              ghc
+              haskell-language-server
+            ];
+          };
+          apps.default = {
+            type = "app";
+            program = "${ghc}/bin/runhaskell";
+          };
+        }
+      );
+}