diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..8392d15
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use flake
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index 62a1808..6a8475f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,5 @@
 *.hi
 *.o
 .DS_Store
+.claude
+.direnv
diff --git a/ch1/baby.hs b/ch1/baby.hs
index 2e1e6d9..2195e3b 100644
--- a/ch1/baby.hs
+++ b/ch1/baby.hs
@@ -1,3 +1,5 @@
+module Baby where
+
 doubleMe x = x + x
 
 doubleUs x y = doubleMe x + doubleMe y
diff --git a/ch10/heathrow.hs b/ch10/heathrow.hs
index 91bb392..4ca9ba2 100644
--- a/ch10/heathrow.hs
+++ b/ch10/heathrow.hs
@@ -1,3 +1,5 @@
+module Heathrow where
+
 import Data.List
 
 data Section = Section { getA :: Int, getB :: Int, getC :: Int }
diff --git a/ch10/solverpn.hs b/ch10/solverpn.hs
index 8b6d555..a479714 100644
--- a/ch10/solverpn.hs
+++ b/ch10/solverpn.hs
@@ -1,3 +1,5 @@
+module SolverPN where
+
 solveRPN :: String -> Double
 solveRPN = head . foldl foldingFunction [] . words
     where   foldingFunction (x:y:ys) "*" = (y * x):ys
diff --git a/ch11/cmaybe.hs b/ch11/cmaybe.hs
index 7fe8e70..61d149c 100644
--- a/ch11/cmaybe.hs
+++ b/ch11/cmaybe.hs
@@ -1,3 +1,5 @@
+module CMaybe where
+
 data CMaybe a = CNothing | CJust Int a deriving Show
 
 instance Functor CMaybe where
diff --git a/ch11/fmapping_io.hs b/ch11/fmapping_io.hs
index a6304db..c631515 100644
--- a/ch11/fmapping_io.hs
+++ b/ch11/fmapping_io.hs
@@ -1,3 +1,5 @@
+module FmappingIO where
+
 import Data.Char
 import Data.List
 
diff --git a/ch11/iofunctor.hs b/ch11/iofunctor.hs
index 0e87a42..edc1278 100644
--- a/ch11/iofunctor.hs
+++ b/ch11/iofunctor.hs
@@ -1,3 +1,5 @@
+module IOFunctor where
+
 main = do 
     line <- fmap reverse getLine
     putStrLn $ "You said " ++ line ++ " backwards!"
diff --git a/ch13/knight.hs b/ch13/knight.hs
index 4ba2904..36a5e0e 100644
--- a/ch13/knight.hs
+++ b/ch13/knight.hs
@@ -1,3 +1,5 @@
+module Knight where
+
 type KnightPos = (Int, Int)
 type KnightPath = [KnightPos]
 
diff --git a/ch14/difflist.hs b/ch14/difflist.hs
index c98d064..1377d83 100644
--- a/ch14/difflist.hs
+++ b/ch14/difflist.hs
@@ -1,3 +1,5 @@
+module DiffList where
+
 import Control.Monad.Writer
 
 newtype DiffList a = DiffList { getDiffList :: [a] -> [a] }
diff --git a/ch14/knight-monadic.hs b/ch14/knight-monadic.hs
index 67ee42a..2abbcf1 100644
--- a/ch14/knight-monadic.hs
+++ b/ch14/knight-monadic.hs
@@ -1,3 +1,5 @@
+module KnightMonadic where
+
 import Control.Monad
 type KnightPos = (Int, Int)
 type KnightPath = [KnightPos]
diff --git a/ch14/monadic.hs b/ch14/monadic.hs
index b0cd43f..f5b5650 100644
--- a/ch14/monadic.hs
+++ b/ch14/monadic.hs
@@ -1,3 +1,5 @@
+module Monadic where
+
 import Control.Monad.Writer
 
 keepSmall :: Int -> Writer [String] Bool 
diff --git a/ch14/prob.hs b/ch14/prob.hs
index f2cf393..798e4ce 100644
--- a/ch14/prob.hs
+++ b/ch14/prob.hs
@@ -1,3 +1,5 @@
+module Prob where
+
 import Data.Ratio
 import Data.Bifunctor
 import Control.Monad
diff --git a/ch14/random.hs b/ch14/random.hs
index c4eb85c..7f5e3db 100644
--- a/ch14/random.hs
+++ b/ch14/random.hs
@@ -1,3 +1,5 @@
+module Random14 where
+
 import System.Random
 import Control.Monad.State
 
@@ -9,4 +11,4 @@ threeCoins = do
     a <- randomSt
     b <- randomSt
     c <- randomSt
-    return (a, b, c)
\ No newline at end of file
+    return (a, b, c)
diff --git a/ch14/reader.hs b/ch14/reader.hs
index af3ea6a..2fa1261 100644
--- a/ch14/reader.hs
+++ b/ch14/reader.hs
@@ -1,3 +1,5 @@
+module Reader where
+
 addStuff :: Int -> Int
 addStuff = do
     a <- (*2)
diff --git a/ch14/ropewalker.hs b/ch14/ropewalker.hs
index 152fedd..49064b3 100644
--- a/ch14/ropewalker.hs
+++ b/ch14/ropewalker.hs
@@ -1,3 +1,5 @@
+module RopeWalker where
+
 -- In the previous chapter, we used the monadic aspects of Maybe 
 -- to simulate birds landing on the balancing pole of a tightrope
 -- walker. As an exercise, you can rewrite that with the error 
diff --git a/ch14/stack.hs b/ch14/stack.hs
index 8f0c5b6..2615ceb 100644
--- a/ch14/stack.hs
+++ b/ch14/stack.hs
@@ -1,3 +1,5 @@
+module Stack where
+
 import Control.Monad.State
 
 type Stack = [Int]
diff --git a/ch15/filesystem.hs b/ch15/filesystem.hs
index c8147d5..9c3a5dd 100644
--- a/ch15/filesystem.hs
+++ b/ch15/filesystem.hs
@@ -1,3 +1,5 @@
+module Filesystem where
+
 import Data.List (break)
 
 x -: f = f x
diff --git a/ch15/tree.hs b/ch15/tree.hs
index 9f1f234..5c139ce 100644
--- a/ch15/tree.hs
+++ b/ch15/tree.hs
@@ -1,3 +1,5 @@
+module Tree15 where
+
 data Tree a = Empty | Node a (Tree a) (Tree a)
     deriving Show
 
diff --git a/ch2/factorial.hs b/ch2/factorial.hs
index 4f8ad4e..c09134b 100644
--- a/ch2/factorial.hs
+++ b/ch2/factorial.hs
@@ -1,3 +1,5 @@
+module Factorial where
+
 factorial :: Integer -> Integer
 factorial n = product [1..n]
 
diff --git a/ch3/lucky.hs b/ch3/lucky.hs
index 08a9f7f..e7b502f 100644
--- a/ch3/lucky.hs
+++ b/ch3/lucky.hs
@@ -1,3 +1,5 @@
+module Lucky where
+
 lucky :: Int -> String
 lucky 7 = "LUCKY NUMBER SEVEN!"
 lucky x = "Sorry, you're out of luck, pal!"
diff --git a/ch4/maximum.hs b/ch4/maximum.hs
index 82f1d33..94f2903 100644
--- a/ch4/maximum.hs
+++ b/ch4/maximum.hs
@@ -1,3 +1,5 @@
+module Maximum where
+
 maximum' :: (Ord a) => [a] -> a
 maximum' [] = error "maximum of empty list!"
 maximum' [x] = x
diff --git a/ch7/deriving.hs b/ch7/deriving.hs
index c235787..bca016b 100644
--- a/ch7/deriving.hs
+++ b/ch7/deriving.hs
@@ -1,3 +1,5 @@
+module Deriving where
+
 data Person = Person { firstName :: String
 , lastName :: String
 , age :: Int} deriving (Eq, Show, Read)
diff --git a/ch7/lockers.hs b/ch7/lockers.hs
index d9eb103..3b4d739 100644
--- a/ch7/lockers.hs
+++ b/ch7/lockers.hs
@@ -1,3 +1,5 @@
+module Lockers where
+
 import qualified Data.Map as Map
 
 data LockerState = Taken | Free deriving (Show, Eq)
diff --git a/ch7/modules.hs b/ch7/modules.hs
index 547efcd..c5a75b7 100644
--- a/ch7/modules.hs
+++ b/ch7/modules.hs
@@ -1,3 +1,5 @@
+module Modules where
+
 import Data.List
 import Data.Char
 import qualified Data.Map as Map
diff --git a/ch7/ownlist.hs b/ch7/ownlist.hs
index 3775078..1df7e38 100644
--- a/ch7/ownlist.hs
+++ b/ch7/ownlist.hs
@@ -1,3 +1,5 @@
+module OwnList where
+
 infixr 7 :-:
 data List a = Empty | a :-: (List a) deriving (Show, Read, Eq, Ord)
 
diff --git a/ch7/typesyn.hs b/ch7/typesyn.hs
index ee04db4..53eeb14 100644
--- a/ch7/typesyn.hs
+++ b/ch7/typesyn.hs
@@ -1,3 +1,5 @@
+module TypeSyn where
+
 type PhoneNumber = String
 type Name = String
 type PhoneBook = [(Name, PhoneNumber)]
diff --git a/ch7/yesno.hs b/ch7/yesno.hs
index ec8a9ee..8682131 100644
--- a/ch7/yesno.hs
+++ b/ch7/yesno.hs
@@ -1,3 +1,5 @@
+module YesNo where
+
 import Traffic
 import Tree
 
diff --git a/ch8/forever.hs b/ch8/forever.hs
index 60c44a4..32eedb6 100644
--- a/ch8/forever.hs
+++ b/ch8/forever.hs
@@ -1,3 +1,5 @@
+module Forever where
+
 import Control.Monad
 import Data.Char
 import System.IO
diff --git a/ch8/form.hs b/ch8/form.hs
index 7ae898e..f707b52 100644
--- a/ch8/form.hs
+++ b/ch8/form.hs
@@ -1,3 +1,5 @@
+module Form where
+
 import Control.Monad
 
 main = do
diff --git a/ch8/helloworld.hs b/ch8/helloworld.hs
index f91e3f6..57a063d 100644
--- a/ch8/helloworld.hs
+++ b/ch8/helloworld.hs
@@ -1 +1,3 @@
+module HelloWorld where
+
 main = putStrLn "Hello, world"
\ No newline at end of file
diff --git a/ch8/putStr.hs b/ch8/putStr.hs
index 1348676..f6b972d 100644
--- a/ch8/putStr.hs
+++ b/ch8/putStr.hs
@@ -1,3 +1,5 @@
+module PutStr where
+
 main = do
     putStr "hey, "
     putStr "I'm "
diff --git a/ch8/reverse.hs b/ch8/reverse.hs
index f6ac08a..b9dc2d6 100644
--- a/ch8/reverse.hs
+++ b/ch8/reverse.hs
@@ -1,3 +1,5 @@
+module Reverse where
+
 main = do
     line <- getLine
     if null line
diff --git a/ch8/rock.hs b/ch8/rock.hs
index 4d03c99..66edcec 100644
--- a/ch8/rock.hs
+++ b/ch8/rock.hs
@@ -1,3 +1,5 @@
+module Rock where
+
 main = do
     putStrLn "Hello, what's your name?"
     name <- getLine
diff --git a/ch8/rock2.hs b/ch8/rock2.hs
index 88ebcd3..2845892 100644
--- a/ch8/rock2.hs
+++ b/ch8/rock2.hs
@@ -1,3 +1,5 @@
+module Rock2 where
+
 import Data.Char
 
 main = do
diff --git a/ch8/when.hs b/ch8/when.hs
index 799d08f..1ab678a 100644
--- a/ch8/when.hs
+++ b/ch8/when.hs
@@ -1,3 +1,5 @@
+module When where
+
 import Control.Monad
 
 main = do
diff --git a/ch9/appendtodo.hs b/ch9/appendtodo.hs
index 49aa196..249b209 100644
--- a/ch9/appendtodo.hs
+++ b/ch9/appendtodo.hs
@@ -1,3 +1,5 @@
+module AppendTodo where
+
 import System.IO
 
 main = do
diff --git a/ch9/arg-test.hs b/ch9/arg-test.hs
index ae83dfa..bd67404 100644
--- a/ch9/arg-test.hs
+++ b/ch9/arg-test.hs
@@ -1,3 +1,5 @@
+module ArgTest where
+
 import System.Environment
 import Data.List
 
diff --git a/ch9/bytestringcopy.hs b/ch9/bytestringcopy.hs
index 4401d8a..a97549f 100644
--- a/ch9/bytestringcopy.hs
+++ b/ch9/bytestringcopy.hs
@@ -1,3 +1,5 @@
+module ByteStringCopy where
+
 import System.Environment
 import System.Directory
 import System.IO
diff --git a/ch9/capslocker.hs b/ch9/capslocker.hs
index 1efd973..a8a03dd 100644
--- a/ch9/capslocker.hs
+++ b/ch9/capslocker.hs
@@ -1,3 +1,5 @@
+module CapsLocker where
+
 import Control.Monad
 import Data.Char
 
diff --git a/ch9/deletetodo.hs b/ch9/deletetodo.hs
index f41bdea..28e23a7 100644
--- a/ch9/deletetodo.hs
+++ b/ch9/deletetodo.hs
@@ -1,3 +1,5 @@
+module DeleteTodo where
+
 import System.IO
 import System.Directory
 import Data.List
diff --git a/ch9/girlfriend-caps.hs b/ch9/girlfriend-caps.hs
index 8c81ba1..e66de0d 100644
--- a/ch9/girlfriend-caps.hs
+++ b/ch9/girlfriend-caps.hs
@@ -1,3 +1,5 @@
+module GirlfriendCaps where
+
 import System.IO
 import Data.Char
 
diff --git a/ch9/girlfriend.hs b/ch9/girlfriend.hs
index b3dd315..58e120a 100644
--- a/ch9/girlfriend.hs
+++ b/ch9/girlfriend.hs
@@ -1,3 +1,5 @@
+module Girlfriend where
+
 import System.IO
 
 main = do
diff --git a/ch9/guess_the_number.hs b/ch9/guess_the_number.hs
index 7d4b986..bf512c8 100644
--- a/ch9/guess_the_number.hs
+++ b/ch9/guess_the_number.hs
@@ -1,3 +1,5 @@
+module GuessTheNumber where
+
 import System.Random
 import Control.Monad(when)
 
diff --git a/ch9/palindrome.hs b/ch9/palindrome.hs
index 641f93e..0f51edf 100644
--- a/ch9/palindrome.hs
+++ b/ch9/palindrome.hs
@@ -1,3 +1,5 @@
+module Palindrome where
+
 main = interact respondPalindrome
 
 respondPalindrome :: String -> String
diff --git a/ch9/random.hs b/ch9/random.hs
index 77b6841..94d19b9 100644
--- a/ch9/random.hs
+++ b/ch9/random.hs
@@ -1,3 +1,5 @@
+module Random where
+
 import System.Random
 
 threeCoins :: StdGen -> (Bool, Bool, Bool)
diff --git a/ch9/random_string.hs b/ch9/random_string.hs
index abea2d1..a7fcc62 100644
--- a/ch9/random_string.hs
+++ b/ch9/random_string.hs
@@ -1,3 +1,5 @@
+module RandomString where
+
 import System.Random
 
 main = do
diff --git a/ch9/shortlinesonly.hs b/ch9/shortlinesonly.hs
index 8dd6dcb..943ce42 100644
--- a/ch9/shortlinesonly.hs
+++ b/ch9/shortlinesonly.hs
@@ -1,3 +1,5 @@
+module ShortLinesOnly where
+
 main = do
     contents <- getContents
     putStr (shortLinesOnly contents)
diff --git a/ch9/shortonly.hs b/ch9/shortonly.hs
index 40e8e24..d5cc1aa 100644
--- a/ch9/shortonly.hs
+++ b/ch9/shortonly.hs
@@ -1,3 +1,5 @@
+module ShortOnly where
+
 main = interact shortLinesOnly
 
 shortLinesOnly :: String -> String
diff --git a/ch9/todo.hs b/ch9/todo.hs
index 65855ed..1033df3 100644
--- a/ch9/todo.hs
+++ b/ch9/todo.hs
@@ -1,3 +1,5 @@
+module Todo where
+
 -- todo check that index is not out of bounds
 -- todo check that the index is a number
 
diff --git a/flake.nix b/flake.nix
index 683962c..e4d28a4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -11,8 +11,19 @@
       let
         pkgs = nixpkgs.legacyPackages.${system};
         
-        haskellPackages = pkgs.haskell.packages.ghc9122;
-        
+        haskellPackages = pkgs.haskell.packages.ghc9122.override {
+          overrides = self: super: {
+            brick = pkgs.haskell.lib.overrideCabal super.brick (oldAttrs: {
+              version = "2.9";
+              src = pkgs.fetchFromGitHub {
+                owner = "jtdaugherty";
+                repo = "brick";
+                rev = "13fc9ede648de359366ed1d2b865fbd847fb2dc5";
+                sha256 = "sha256-t+S7BkKYuq71rsiffOTuwgnmlWwGPlp5dxHZscsu9w8=";
+              };
+            });
+          };
+        };        
         ghcWithPackages = haskellPackages.ghcWithPackages (ps: with ps; [
           # Basic packages that might be useful for the examples
         ]);
@@ -47,4 +58,4 @@
           '';
         };
       });
-}
\ No newline at end of file
+}