Mark Carroll <[EMAIL PROTECTED]> writes:
> For fairly flat things, the updates using field labels are okay. However,
> when I have a function that needs to tweak various bits of various "deep"
> fields, based on various conditions, then it gets really ugly, not least
> because of the conditions: foo { bar = baz } becomes,
> let old = bar foo in foo { bar = if cond then f old else old }
> or whatever. Do I need such a let for each component and sub-component of
> the object that has a child that may be modified, or will
> foo { bar = if cond then f (bar foo) else bar foo }
> be suitably optimised?
If the pattern is very common, how about just naming it?
perhaps cond f field = if cond then f field else field
foo { bar = perhaps cond0 f (bar foo)
, wib = perhaps cond1 g (wib foo) }
Regards,
Malcolm
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