Re: [Haskell-cafe] Is there any way to parametrize a value update using record syntax?

On 07.09.2011 00:56, Brandon Allbery wrote:

2011/9/6 Poprádi Árpád mailto:popradi_arpad@freemail.hu>

updateData1 :: X -> MonadicEnv() updateData1 d = do; env <- get; put env {data1 = d}

...

updateData1 d = modify (\r -> r {data1 = d})

But there is, sadly, no eta-reduced version of record update to make the "\r -> r ..." boilerplate go away; recognition of the syntax requires an expression before the braces. (Consider the ambiguity of the eta-reduced expression "modify {data1 = d}".) Also, and much more annoyingly, "data1" must be constant.

In principle ambiguity could be resolved with a slash: modyfy \{data = d} But that's from land of hypothetical language extension and dog headed people.