Module Control.Findall

getAllValues :: a -> IO [a]   

Gets all values of an expression (currently, via an incomplete depth-first strategy). Conceptually, all values are 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 values contain unbound variables. Similar to Prolog's findall.

allValues :: a -> [a]   

Returns all values of an expression (currently, via an incomplete depth-first strategy). Conceptually, all values are 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 values contain 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

someValue :: a -> a   

Returns some value for an expression (currently, via an incomplete depth-first strategy). 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.

Further infos:

• externally defined

oneValue :: a -> Maybe a   

Returns just one value for an expression (currently, via an incomplete depth-first strategy). 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

allSolutions :: Data a => (a -> Bool) -> [a]   

Returns all values satisfying a predicate, i.e., all arguments such that the predicate applied to the argument can be evaluated to True (currently, via an incomplete depth-first strategy). In PAKCS, the evaluation suspends as long as the predicate expression contains unbound variables or the computed values contain 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.

someSolution :: Data a => (a -> Bool) -> a   

Returns some value satisfying a predicate, i.e., some argument such that the predicate applied to the argument can be evaluated to True (currently, via an incomplete depth-first strategy). If there is no value satisfying the predicate, the computation fails.

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

oneSolution :: Data a => (a -> Bool) -> Maybe a   

Returns just one value satisfying a predicate. If there is no such value, Nothing is returned

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.

Further infos:

• externally defined

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 require 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