haskell - How to "compose" Iso's? -

here type:

newtype sanedate = sanedate universaltime    deriving (show, eq, typeable, generic) makewrapped ''sanedate

now need iso type:

reprbuild :: iso' (maybe universaltime) (fist sanedate)

i did this:

reprbuild = iso    (\ t -> first (sanedate <$> t) )    (\ sane_first -> fmap (^. _wrapped) $ getfirst sane_first  )

but have impression i'm working extra-hard. there (shorter) way of writing reprbuild iso composition of things?

recent versions of lens have built in:

reprbuild = coerced

of course, requires safe coercions available since 7.10; backwards compatibility use manual approach mapping.

M16