lambda - Does Haskell provide an idiom for pattern matching against many possible data constructors? -

working on haskell project, i'm dealing event data type fsnotify package. constructors event all:

added filepath utctime modified filepath utctime removed filepath utctime 

in code, i'm interested in extracting filepath event , doing same action regardless of type constructor; because of this, i'm tempted make lambda.

unfortunately, code suffers reduced readability when drop case expression lambda pattern match against 3 cases; there built-in idiom extract filepath in 1 expression without having manually pattern match, given relative homogeneity of type constructors?

i've tried passing expression anonymous function in call watchdir action:

 wm <- startmanager  sw <- watchdir wm "." (\_ -> true) (\(_ f t) -> putstrln f) 

but, predictably, don't-care value in lambda's pattern match causes parse error.

the simplest way reflect homogenity of alternatives in type declaration, instead of observing it:

data action = added | modified | removed  data event = fileevent action filepath utctime | otherevent ...  f :: event -> filepath f (fileevent _ path _) = path 

in general, haskell has no way know constructor alternatives have same number of arguments , same type, no, can't abstract on choice of alternative.