Re: [Haskell-beginners] how to skip pattern match error when applying a mapM_

Just gamma <- get_position' (h5gamma d) 0 Just delta <- get_position' (h5delta d) idx Just wavelength <- get_position' (h5wavelength d) 0

is asking for a trouble down the road. Use a case to pattern match on nothing, (or `maybe`, or LambdaCase if you are into extensions).

I tought that was the purpose of the Monad to avoid writting these boillerplate ? What I am missing ? Cheers Frederic