From fb301042ac6df183bb3c59a2d036844ae5c094d0 Mon Sep 17 00:00:00 2001
From: Steven <steven.vasilogianis@gmail.com>
Date: Tue, 4 Jun 2019 21:34:40 -0400
Subject: Removed shadowed bindings & redundant imports

---
 src/Main.hs | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

(limited to 'src/Main.hs')

diff --git a/src/Main.hs b/src/Main.hs
index e6ed4e2..190e997 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,12 +1,8 @@
-{-# LANGUAGE FlexibleContexts #-}
-
 module Main where
 
 import           Data.List
 import           Data.Matrix
-import           Data.String
 import           System.Environment
-import           System.IO
 
 main :: IO ()
 main = do
@@ -16,26 +12,26 @@ main = do
 
 data Square = O | X | Qu deriving (Show, Eq)
 
-solve :: (Eq t, Num t) => t -> [Matrix Square]
+solve :: (Eq n, Num n) => n -> [Matrix Square]
 solve n = nub $ solveN n
   where
-    solveN 1 = solve [initBoard]
-    solveN x = solve (solveN (x-1))
+    solveN 1 = solve' [initBoard]
+    solveN x = solve' (solveN (x-1))
+    solve' bs = concatMap (\bn -> map ((`placeQueen` bn)) (openPositions bn)) bs
     initBoard = matrix 8 8 (const O)
-    solve bs = concatMap (\b -> map (\p -> placeQueen p b) (openPositions b)) bs
     openPositions b = [(i,j) | i <- [1..8], j <- [1..8], b ! (i,j) == O ]
     placeQueen p b = mark Qu p $ markAttacks b
       where
-        markAttacks b = markAll X positions b
-        positions = concat $ map walk directions
+        markAttacks bo = markAll X positions bo
+        positions = concatMap walk directions
         step (fx,fy) = (\(k,l) -> (fx k, fy l))
         walk s = takeWhile inBounds $ iterate (step s) $ step s p
-        directions = let a = (+1); s = (subtract 1); n = (id)
-                     in [   (a,n),(s,n) -- up, down
-                          , (n,a),(n,s) -- right, left, diags:
-                          , (a,a),(a,s),(s,a),(s,s) ]
+        directions = let a = (+1); s = subtract 1; nc = id
+                     in [   (a,nc),(s,nc)             -- up, down
+                          , (nc,a),(nc,s)             -- right, left
+                          , (a,a),(a,s),(s,a),(s,s) ] -- diags
         inBounds (i,j) = i >= 1 && i <= nrows b && j >= 1 && j <= ncols b
-        markAll x [] b = b
-        markAll x (p:ps) b = let nb = mark x p b
-                             in markAll x ps nb
-        mark x p b = setElem x p b
+        markAll _ [] mb = mb
+        markAll x (mp:mps) mb = let nb = mark x mp mb
+                             in markAll x mps nb
+        mark x mp mb = setElem x mp mb
-- 
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