cabal, to make the extension happy

haskell/Main.hs

@@ -0,0 +1,4 @@
+module Main where
+
+main :: IO ()
+main = putStrLn "Hello, Haskell!"

haskell/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

haskell/all_even.hs

@@ -3,9 +3,18 @@ module Main where
   allEven [] = []
   allEven (h:t) = if even h then h:allEven t else allEven t
 
-  -- >>> :t allEven
-  -- allEven :: [Integer] -> [Integer]
-  --
+  allEven2 :: [Integer] -> [Integer]
+  allEven2 xs = [x | x <- xs, even x]
+
+  allEven3 :: [Integer] -> [Integer]
+  allEven3 = filter even
+
+  -- >>> allEven [1, 2, 3, 4, 5, 6]
+  -- [2,4,6]
+  -- >>> allEven2 [1, 2, 3, 4, 5, 6]
+  -- [2,4,6]
+  -- >>> allEven3 [1, 2, 3, 4, 5, 6]
+  -- [2,4,6]
 
   main :: IO()
   main =

haskell/haskell.cabal

@@ -0,0 +1,24 @@
+cabal-version:       >=1.10
+-- Initial package description 'haskell.cabal' generated by 'cabal init'.
+-- For further documentation, see http://haskell.org/cabal/users-guide/
+
+name:                haskell
+version:             0.1.0.0
+-- synopsis:
+-- description:
+-- bug-reports:
+-- license:
+license-file:        LICENSE
+author:              Jason Staten
+maintainer:          code@jxs.me
+-- copyright:
+-- category:
+build-type:          Simple
+
+executable haskell
+  main-is:             Main.hs
+  -- other-modules:
+  -- other-extensions:
+  build-depends:       base >=4.12 && <4.13
+  -- hs-source-dirs:
+  default-language:    Haskell2010