>
> modifyConfig :: (Config -> a) -> (a -> a) -> Config -> Config
> modifyConfig fr fv a = a { fr = fv (fr a)
>
I like this Idea. The only problem I see is this: if I'm trying to write
code that is very generic and abstract, how does the compiler know if the
update
> a { fr = 5 }
is targeting a field fr of the record a, or a variable fr, which is in
scope and "points to" a first-class field. The difference depends on the
record in question, so the code would work differently depending on the
context. I would think it would have to be something like
> a { :fr = 5 }
or something else syntactically distinct from current record update syntax.
With this and a few more conveniences on record syntax, lenses could go
away. For example, I'd love to see a "lambda update" syntax. For example
instead of:
> setName n r = r {name = n}
we'd write
> setName n = \{name = n}
I'd also like to see an "Update field by" syntax. Instead of
> addMr r = r { name = "Mr. " ++ (name r) }
we'd write
> addMr r = r { name => ("Mr. "++) }
or combining the previous 2:
> addMr = \{name=>("Mr. "++)}
feels very terse and "Haskelly" to me.
Regards,
--J Arthur
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