On 11 September 2010 18:21, Jonathan Geddes <geddes.jonat...@gmail.com> wrote:
>>someUpdate :: MyRecord -> MyRecord
>>someUpdate myRecord = myRecord
>> { field1 = f $ field1 myRecord
>> , field2 = g $ field2 myRecord
>> , field3 = h $ filed3 myRecord
>> }
Applicatively, using no additional libraries, is how I do it:
updateAllThree :: MyRecord -> MyRecord
updateAllThree = (\s a b c -> s { field1 = f a, field2 = g b, field3 = h c})
<*> field1 <*> field2 <*> field3
Note - (<$>) is not used, and the left hand function has one extra
argument. This style exploits the fact that (<*>) is the Startling (S)
combinator.
Unfortunately, I haven't worked out how to do nested records in this style.
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