Question

I have defined a type as:

type Register = Int

I’m also able to read in a list of numbers from a list of Strings using a function like:

readInt :: String -> Int
readInt s = read s :: Int

now, using readInt on a list like readInt "12 32 11" gives me [12, 32, 11] which is of type [Int].

My question is: instead of [Int], how can I get [Register].

I tried:

readRegister :: String -> Register
readRegister s = read s :: Register

but as I guessed, it doesn’t seem to be valid syntax.

Answer 1

Your definition of Register is a type alias, i.e. it is interchangeable with its right hand side, i.e. here with Int.

But you state that readInt "12 32 11" would yield [12,32,11] :: [Int]. This is impossible given your type signature of readInt :: String -> Int. Perhaps you could show us a bit more of your code.