Ah, a fine idea. I'll do that anyway; maybe others will have even better ideas, but that's a good start S | -----Original Message----- | From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Björn | Bringert | Sent: 14 March 2007 14:28 | To: Simon Peyton-Jones | Cc: haskell-cafe@haskell.org | Subject: Re: [Haskell-cafe] Read Instance for UArray won't port to linux | | Simon Peyton-Jones wrote: | > | The error in linux is: | > | Illegal instance declaration for `Read (UArray Int Double)' | > | (The instance type must be of form (T a b c) | > | where T is not a synonym, and a,b,c are distinct type variables) | > | In the instance declaration for `Read (UArray Int Double)' | > | | > | Why does it want three parameters for the instance type? I am baffled by | > | this. | > | > It's saying that in Haskell 98 you can have | > instance Read (UArray a b) | > (for type variables a, b) but not | > instance Read (UArray Int Double) | > | > (As Spencer says, use -fglasgow-exts to lift the H98 restriction.) | > | > However, you mis-read the error message to say "the instance type must have three parameters", which | isn't what I meant at all! I was trying to use an example of the general form, but conveyed the wrong | idea. | > | > I can see why you read it that way. Now you understand, can you give me a better error message? | | I'm not the original poster, but what about just changing it to "The | instance type must be of the form (T a1 ... an) where T is not a | synonym, and a1 ... an are distinct type variables)"? | | /Björn | _______________________________________________ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe