[Haskell-cafe] the Haskell "with" "pattern"?
jules at jellybean.co.uk
Wed Aug 6 11:44:52 EDT 2008
Johan Tibell wrote:
> 2008/8/6 Galchin, Vasili <vigalchin at gmail.com>:
>> 1) Is there a common assumed semantics across all of the Haskell "with"
>> things? withString? withData?
> You probably knew this already but there's nothing in the "with idiom"
> that prevents the resource to escape.
And, it doesn't always matter. Some withs are more unsafe that others :)
if the 'with' constructs a nice ordinary heap allocated haskell
structure from the external resource then it may not matter one jot if
it escapes: it may be out-of-date, perhaps, but still a useful data value.
On the other hand sometimes it does matter....
> Oleg recently wrote about
> (lightweight) monadic regions and how they can statically assure that
> this doesn't happen.
Which is clever.
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