Re: [Haskell-cafe] Bad "let..do" syntax

Thanks, I had forgotten about multiple let bindings as something it might be looking for. I guess in this case the curly braces aren't too bad, given that this situation doesn't come up so much, and it would let me keep the indentation consistent. And yes, this is just a boiled-down version of the original code, where sum [0.. x+1] wasn't an option. -Chad On 5/17/07, David House wrote:

On 17/05/07, Chad Scherrer wrote:

...

But GHC complains of "Empty 'do' construct".

Because it takes the indented following lines as being new bindings in the let-block. The trick is to intent them past the 'sum':

let b = sum $ do y <- [0..x + 1] return y

Or to bypass layout altogether:

let { b = sum $ do y <- [0..x + 1] return y }

(Of course, in this specific case I'd write sum [0..x + 1], but I guess that this is an example of a general case.)

-- -David House, dmhouse@gmail.com