[Haskell-cafe] Extensible Effects & Multiple Operations

Justin Bailey jgbailey at gmail.com
Mon Jul 21 16:02:56 UTC 2014

On Thu, Jul 17, 2014 at 3:32 PM, Tobias Florek <haskell at ibotty.net> wrote:
>     data OpenFile v = Read (Char -> v)
>                     | EOF  (Bool -> v)
>       deriving Typeable

That worked! Removing the type variable (`a`) from `OpenFile` did the
trick. I was carrying too much type information around for what I
wanted to do (e.g., OpenFile Char and OpenFile Bool). Removing that
extra piece of info allowed me to write `runOpenFile` just like I



More information about the Haskell-Cafe mailing list