`Fix.SOLVER`

A solver is a higher-order function that computes the least solution of a monotone system of equations.

A right-hand side, when supplied with a valuation that gives meaning to its free variables, evaluates to a property. More precisely, a right-hand side is a monotone function of valuations to properties.

A system of equations is a mapping of variables to right-hand sides.

`lfp eqs`

produces the least solution of the system of monotone equations `eqs`

.

It is guaranteed that, for each variable `v`

, the application `eqs v`

is performed at most once (whereas the right-hand side produced by this application is, in general, evaluated multiple times). This guarantee can be used to perform costly pre-computation, or memory allocation, when `eqs`

is applied to its first argument.

When `lfp`

is applied to a system of equations `eqs`

, it performs no actual computation. It produces a valuation, `get`

, which represents the least solution of the system of equations. The actual fixed point computation takes place, on demand, when `get`

is applied.