Re: Bang patterns

On Mon, Feb 04, 2013 at 01:21:31PM -0800, Johan Tibell wrote:

On Sun, Feb 3, 2013 at 4:44 PM, Ben Millwood wrote:

...

I have two proposals, I suppose: - make bang patterns in let altogether invalid

I would prefer it to be valid. It's the syntactically most lightweight option we have to force some thunks before using the resulting values in a constructor that we have. Example

let !x = ... !y = ... in C x y

The alternative would be

let x = ... y = ... in x `seq` y `seq` C x y

which obscures the code much more.

I'd write (C $! x) $! y. We could devise a left-associative $! to avoid the use of parentheses here. But my objection was only ever a mild unease in any case, so I'm happy to dismiss it. Ben