.TH "MoreLabels.Hashtbl.HashedType" 3 2024-05-31 OCamldoc "OCaml library"
.SH NAME
MoreLabels.Hashtbl.HashedType \- The input signature of the functor MoreLabels.Hashtbl.Make.
.SH Module type
Module type   MoreLabels.Hashtbl.HashedType
.SH Documentation
.sp
Module type
.BI "HashedType"
 = 
.B sig end

.sp
The input signature of the functor 
.ft B
MoreLabels\&.Hashtbl\&.Make
.ft R
\&.

.sp

.sp
.sp
.I type t 

.sp
The type of the hashtable keys\&.

.sp

.I val equal 
: 
.B t -> t -> bool
.sp
The equality predicate used to compare keys\&.

.sp

.I val hash 
: 
.B t -> int
.sp
A hashing function on keys\&. It must be such that if two keys are
equal according to 
.ft B
equal
.ft R
, then they have identical hash values
as computed by 
.ft B
hash
.ft R
\&.
Examples: suitable (
.ft B
equal
.ft R
, 
.ft B
hash
.ft R
) pairs for arbitrary key
types include
.sp
\-        (
.ft B
(=)
.ft R
, 
.ft B
MoreLabels\&.Hashtbl\&.HashedType\&.hash
.ft R
) for comparing objects by structure
(provided objects do not contain floats)
.sp
\-        (
.ft B
(fun x y \-> compare x y = 0)
.ft R
, 
.ft B
MoreLabels\&.Hashtbl\&.HashedType\&.hash
.ft R
)
for comparing objects by structure
and handling 
.ft B
nan
.ft R
correctly
.sp
\-        (
.ft B
(==)
.ft R
, 
.ft B
MoreLabels\&.Hashtbl\&.HashedType\&.hash
.ft R
) for comparing objects by physical
equality (e\&.g\&. for mutable or cyclic objects)\&.


.sp