rev_assoc
hol88Lib.rev_assoc : ''a -> ('b * ''a) list -> 'b * ''a
Searches a list of pairs for a pair whose second component equals a specified value.
rev_assoc y [(x1,y1),...,(xn,yn)] returns the first (xi,yi) in the
list such that yi equals y. The lookup is done on an eqtype, i.e.,
the SML implementation must be able to decide equality for the type of
y.
Failure
Fails if no matching pair is found. This will always be the case if the list is empty.
Example
- rev_assoc 2 [(1,4),(3,2),(2,5),(2,6)];
(3, 2) : (int * int)
Comments
Superseded by Lib.rev_assoc and Lib.assoc2.