Question

I am attempting to create a type synonym that looks something like this:

data Result = Either String [Token]

I’m having difficulty because while this code compiles, when I attempt to create a Result with a [Token], haskell complains

    Not in scope: data constructor `Result'

How can I define a type synonym with a constructor that works?!

Answer 1

How are you trying to create a Result??
The correct way is:

If you declare it as a data:

data Result = Result (Either String [Token])

f :: Result
f = (Result (Left "test"))

Or, if you declare as a type:

type Result = Either String [Token]

f :: Result
f = Left "test"