I agree. My comment is from three years ago, I don't even remember this kata. Looks like I let a bit of frustration get the best of me.

Rounding is ( almost ) never the appropriate solution. If something's wrong, provide the problem, not the solution.

Ah, I didn't see that - it's annoying that it's still unfixed after so long

I added = 0 to the equation

added in JavaScript. already existing in Haskell

fixed

isnt this a duplicate of that issue ?

I don't know how this can be wrong - it says it's expecting exactly what I'm returning!

Falsifiable (after 2 tests and 6 shrinks):
  1.0e-2
  0.0
  0.0
expected: Single (-0.0)
 but got: Single (-0.0)

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The last line of the description

The suggestion tag should be used for giving potential improvements to the kata itself, this is just a solution

Your solution returns the number passed in, so add(1) returns 1 - if you then do add(1)(2), you're trying to call the number 1 as a function, which causes the error.