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

[Tom Ellis]

On Thu, Aug 14, 2014 at 10:48:34AM +0200, Wojtek Narczyński wrote:
> On 14.08.2014 01:21, Tom Ellis wrote:
> >Perhaps I don't grasp exactly what you're getting at, but this seems easy.
> >Please let me know where my proposed solution fails to provide what you
> >need.
> >
> >I do see that you originally said "In Haskell you'd need two data types: the
> >usual proper Haskell data type, and another which wraps every field in
> >Maybe, facilitates editing, validation, etc.".  You don't actually *need*
> >the version without the Maybe, but you can provide it if you want some
> >additional type safety.
> 
> Yes! This is what I mean.
> 
> But there is much more to validation, than just missing values.
[...]
> 
> The difficulty lies in abundance, ubiquity and complexity of the
> validation rules.
> 
> Empty fields are just an innocent example. The code you provided
> solves it well, but this is just a tip of an iceberg.
> 
> And we still haven't even touched the subject of assisting the user
> to fix the inconsistencies.
> 
> Therefore, quite frankly, I was hoping for radical new ideas how to
> tackle this, when I was starting this thread. DSLs, logic, Attribute
> Grammars, something like that.

Is there a language that gets this right?  If so we can try replicating its
functionality in Haskell.

Tom