Problem 22 Solutions

Solution 1

Yeah, you can recurse this.

range : Int -> Int -> List Int 
range start end = 
    if start == end then
        [end]
    else
        if (start < end) then
          start :: range (start + 1) end
        else 
          start :: range (start - 1) end

Solution 2

Use the range operator (..) and handle reverse order. This is much faster

range : Int -> Int -> List Int 
range start end = 
    if start <= end then
        [start .. end]
    else
        List.reverse [end .. start]

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