Hello Roger, Il 26 gennaio 2022 alle 08:40 Roger Mason ha scritto:
I attempt to parse the input: ====================================================== :{ main = do eqatoms <- readFile "Parsing_File/eqatoms.out" Parsec.parse species "test species" eqatoms return :}
Prelude Parsec Text.Parsec Control.Applicative Control.Monad.Identity| Prelude Parsec Text.Parsec Control.Applicative Control.Monad.Identity| Prelude Parsec Text.Parsec Control.Applicative Control.Monad.Identity| Prelude Parsec Text.Parsec Control.Applicative Control.Monad.Identity| Prelude Parsec Text.Parsec Control.Applicative Control.Monad.Identity| <interactive>:250:3: error: ,* Couldn't match type `Either Parsec.ParseError' with `IO' Expected type: IO (String, String) Actual type: Either Parsec.ParseError (String, String) ,* In a stmt of a 'do' block: Parsec.parse species "test species" eqatoms In the expression: do eqatoms <- readFile "Parsing_File/eqatoms.out" Parsec.parse species "test species" eqatoms return In an equation for `main': main = do eqatoms <- readFile "Parsing_File/eqatoms.out" Parsec.parse species "test species" eqatoms return
The problem is with this line
Parsec.parse species "test species" eqatoms
`parse` returns an Either, so you should pattern match on its `Left` and `Right` (using `case` or the `either` function). This has to be done inside a `let` too, because parse is a pure function. Does that help? —F