wearsunscreen/ninety-nine-elm-problems

ninety-nine-elm-problems's Issues

More detailed test results

Going through the book, I find that more details on test failures would have been helpful.
Would you be interested in a patch?

Solution to problem 32 is incorrect as per included test cases.

See title. Here is a slightly modified version of the unit test to demonstrate the problem...

import Html
import List
import Maybe

gcd : Int -> Int -> Int 
gcd a b =
    if b == 0 then  
        a
    else
        gcd b (a % b)

main =
    test |> toString |> Html.text

test : List Bool
test =
    List.map (\(x, y) -> x == y)
        [ ( gcd 36 63, 9 )
        , ( gcd 10 25, 5 )
        , ( gcd 120 120, 120 )
        , ( gcd 2 12, 2 )
        , ( gcd 23 37, 1 )
        , ( gcd 45 330, 15 )
        , ( gcd 24528 65934, 6 )
        , ( gcd 120 -120, 120 )
        , ( gcd -2 12, 2 )
        , ( gcd 37 23, 1 )
        ]

Result: [True,True,True,True,True,True,True,False,True,True]

Suggested fix...

gcd : Int -> Int -> Int 
gcd a b =
    if b == 0 then  
        abs a
    else
        gcd b (a % b)

Result : [True,True,True,True,True,True,True,True,True,True]

Solution to Problem 10 is maybe overcomplicated (?)

I'm new to Elm, but maybe this solution to Problem 10 is more straightforward?

Or maybe the problem itself should be reformulated to require a solution of the desired complexity?

It assumes that the input list is to spec-- each sublist contains only identical elements. It's a bit more ham-fisted than the listed solution, but it passes all the tests.

runLengths : List (List a) -> List ( Int, a )
runLengths xss =
  case xss of
    [] ->
      []
    ys :: yys ->
      case ys of
        [] ->
          runLengths yys
        z :: zs ->
          ( List.length ys, z ) :: runLengths yys