A.hs:1:16: error: [GHC-58481] parse error on input ‘where’

<interactive>:25:1: error: [GHC-88464]
    Variable not in scope: yan
    Suggested fix: Perhaps use ‘tan’ (imported from Prelude)

A.hs:1:16: error: [GHC-58481] parse error on input ‘where’