Module Control.AllValues

getAllValues :: a -> IO [a]   

Gets all values of an expression (similarly to Prolog's findall). Conceptually, the value is computed on a copy of the expression, i.e., the evaluation of the expression does not share any results. In PAKCS, the evaluation suspends as long as the expression contains unbound variables or the computed value contains unbound variables.

getOneValue :: a -> IO (Maybe a)   

Gets one value of an expression. Returns Nothing if the search space is finitely failed. Conceptually, the value is computed on a copy of the expression, i.e., the evaluation of the expression does not share any results. In PAKCS, the evaluation suspends as long as the expression contains unbound variables or the computed value contains unbound variables.

getAllFailures :: a -> (a -> Bool) -> IO [a]   

Returns a list of values that do not satisfy a given constraint.

Example call:

(getAllFailures x c)

Parameters:

• x : an expression (a generator evaluable to various values)
• c : a constraint that should not be satisfied

Returns:

A list of all values of e such that (c e) is not provable

allValues :: a -> [a]   

Returns all values of an expression. Conceptually, the value is computed on a copy of the expression, i.e., the evaluation of the expression does not share any results. In PAKCS, the evaluation suspends as long as the expression contains unbound variables or the computed value contains unbound variables.

Note that this operation is not purely declarative since the ordering of the computed values depends on the ordering of the program rules.

Further infos:

• externally defined

oneValue :: a -> Maybe a   

Returns just one value for an expression. If the expression has no value, Nothing is returned. Conceptually, the value is computed on a copy of the expression, i.e., the evaluation of the expression does not share any results. In PAKCS, the evaluation suspends as long as the expression contains unbound variables or the computed value contains unbound variables.

Note that this operation is not purely declarative since the computed value depends on the ordering of the program rules. Thus, this operation should be used only if the expression has a single value.

Further infos:

• externally defined

someValue :: a -> a   

Returns some value for an expression. If the expression has no value, the computation fails. Conceptually, the value is computed on a copy of the expression, i.e., the evaluation of the expression does not share any results. In PAKCS, the evaluation suspends as long as the expression contains unbound variables or the computed value contains unbound variables.

Note that this operation is not purely declarative since the computed value depends on the ordering of the program rules. Thus, this operation should be used only if the expression has a single value.

isFail :: a -> Bool   

Does the computation of the argument to a head-normal form fail? Conceptually, the argument is evaluated on a copy, i.e., even if the computation does not fail, it has not been evaluated.

rewriteAll :: a -> [a]   

Gets all values computable by term rewriting. In contrast to allValues, this operation does not wait until all "outside" variables are bound to values, but it returns all values computable by term rewriting and ignores all computations that requires bindings for outside variables.

Further infos:

• externally defined

rewriteSome :: a -> Maybe a   

Similarly to rewriteAll but returns only some value computable by term rewriting. Returns Nothing if there is no such value.

Further infos:

• externally defined