`EQKEY`

signatureThe `EQKEY`

signature defines an abstract
type `t`

and provides
equality and `toString`

functions
on values of such type.

```
type t
```

val equal : t * t -> bool

val toString : t -> string

`type`

**t**- The abstract type as described in the overview.

`val`

**equal**: t * t -> bool`(equal (x, y))`

evaluates to`true`

if and only if $x$ and $y$ are equal values of type`t`

.`val`

**toString**: t -> string`(toString k)`

evaluates to a string representation of $x$, a value of type`t`

.