Re: [Haskell-cafe] The Good, the Bad and the GUI

On 13.08.2014 22:49, Steve Schafer wrote:

On Wed, 13 Aug 2014 22:31:31 +0200, Wojtek Narczy?ski wrote:

...

Let's say the user entered:

No, Name, Qty, Price -------------------------------------------- 1. [ ] [99] [10] 2. [Water] [ ] [10] 3. [Juice] [ 1] [ ]

The GUI should display total of 990 Why? Why are any of these erroneous line items included in the total? I would argue that an incomplete or otherwise erroneous line item is not part of the invoice. Say that the error is merely a warning, for example the user entered 'A' which is suspiciously short. I don't know of any (reasonable) online merchant that requires the user to separately enter item, quantity and price. Yes, it is terrible. It's called "accounting".