From 010404abf1321443677efc91d21eb7f93c91a324 Mon Sep 17 00:00:00 2001
From: Jan Sucan <jan@jansucan.com>
Date: Sat, 11 Mar 2023 17:31:29 +0100
Subject: 3_b_6: Add solution

---
 ch03/3_b_6.hs | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 ch03/3_b_6.hs

(limited to 'ch03/3_b_6.hs')

diff --git a/ch03/3_b_6.hs b/ch03/3_b_6.hs
new file mode 100644
index 0000000..74d46ac
--- /dev/null
+++ b/ch03/3_b_6.hs
@@ -0,0 +1,25 @@
+-- Create a function that sorts a list of lists based on the length of each
+-- sublist. (You may want to look at the sortBy function from the Data.List
+-- module.)
+
+import Data.List
+
+myCompare :: [a] -> [a] -> Ordering
+myCompare a b = if len_a < len_b
+                then LT
+                else if len_a == len_b
+                     then EQ
+                     else GT
+  where len_a = length a
+        len_b = length b
+
+mySort :: [[a]] -> [[a]]
+mySort xs = Data.List.sortBy myCompare xs
+
+-- ghci> :l 3_b_6.hs
+-- [1 of 1] Compiling Main             ( 3_b_6.hs, interpreted )
+-- Ok, one module loaded.
+-- ghci> mySort []
+-- []
+-- ghci> mySort [[2, 3], [7, 8, 9, 10], [1], [], [4, 5, 6]]
+-- [[],[1],[2,3],[4,5,6],[7,8,9,10]]
-- 
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