Parse error on input ‘->’ in 'case of' statement in Haskell-CodePudding

module SpaceAge (Planet(..), ageOn) where

data Planet = Mercury
            | Venus
            | Earth
            | Mars
            | Jupiter
            | Saturn
            | Uranus
            | Neptune

ageOn :: Planet -> Float -> Float
ageOn planet seconds = 
  case planet of {
    Mercury -> seconds * 0.2408467
    Venus -> seconds * 0.61519726
    Earth -> seconds * 1
    Mars -> seconds * 1.8808158
    Jupiter -> seconds * 11.862615
    Saturn -> seconds * 29.447498
    Uranus -> seconds * 84.016846
    Neptune -> seconds * 164.79132
  }

Hello, when I compile the above Haskell Code, it gives me

error: parse error on input ‘->’
    |
115 |     Venus -> seconds * 0.61519726

All my cases are vertically aligned, so what's the issue?

Thanks

CodePudding user response：

Writing curly braces indicates to GHC that you don't want to use whitespace layout for determining the block structure, so then you would have to use semicolons to separate each of the cases.

But the preferred way is to just leave out the curly braces:

ageOn' :: Planet -> Float -> Float
ageOn' planet seconds = 
  case planet of
    Mercury -> seconds * 0.2408467
    Venus -> seconds * 0.61519726
    Earth -> seconds * 1
    Mars -> seconds * 1.8808158
    Jupiter -> seconds * 11.862615
    Saturn -> seconds * 29.447498
    Uranus -> seconds * 84.016846
    Neptune -> seconds * 164.79132