From 05ff6d55f6d6b0c8691b737dea2bc160b04178e2 Mon Sep 17 00:00:00 2001 From: Jan Sucan Date: Sat, 11 Mar 2023 13:35:05 +0100 Subject: 3_b_3: Add solution --- README.md | 2 +- ch03/3_b_3.hs | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+), 1 deletion(-) create mode 100644 ch03/3_b_3.hs diff --git a/README.md b/README.md index b264c5d..0157c7f 100644 --- a/README.md +++ b/README.md @@ -55,7 +55,7 @@ more visible in the list the first exercise of a group is in bold italics. | 3_a_2 | yes | | | | **_3_b_1_** | yes | 69 | | | 3_b_2 | yes, in 3_b_1 | | | -| 3_b_3 | | | | +| 3_b_3 | yes | | | | 3_b_4 | | | | | 3_b_5 | | | | | 3_b_6 | | 70 | | diff --git a/ch03/3_b_3.hs b/ch03/3_b_3.hs new file mode 100644 index 0000000..c0d62d5 --- /dev/null +++ b/ch03/3_b_3.hs @@ -0,0 +1,24 @@ +-- Write a function that computes the mean of a list, i.e. the sum of all +-- elements in the list divided by its length. (You may need to use the +-- fromIntegral function to convert the length of the list from an integer into +-- a floating point number.) + +sumOfList [] = 0 +sumOfList (x:xs) = x + (sumOfList xs) + +meanOfList [] = 0 +meanOfList xs = sum / (fromIntegral len) + where sum = sumOfList xs + len = length xs + +-- ghci> :l 3_b_3.hs +-- [1 of 1] Compiling Main ( 3_b_3.hs, interpreted ) +-- Ok, one module loaded. +-- ghci> meanOfList [] +-- 0.0 +-- ghci> meanOfList [1] +-- 1.0 +-- ghci> meanOfList [1, 3] +-- 2.0 +-- ghci> meanOfList [2.3, 4.5, 6.9] +-- 4.566666666666666 -- cgit v1.2.3