Meta.Compare
Custom comparison key.
The Fun.Generic.compare
function consults this key in the metadata of a gist g
before comparing values described by the gist. If a function is found, the values are compared with this function instead.
This can also be used to indicate that you would not like to compare a substructure by always returning 0
(equal), the Compare.ignore
function does that.
type 'a meta := 'a Type.Gist.Meta.t
val mem : 'a meta -> bool
mem m
is true
iff m
has a binding for the key.