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| -rw-r--r-- | README.md | 2 | ||||
| -rw-r--r-- | ch03/3_b_3.hs | 24 |
2 files changed, 25 insertions, 1 deletions
@@ -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 |