Library with some operations for encapsulating search.
Note that some of these operations are not fully declarative,
i.e., the results depend on the order of evaluation and program rules.
There are newer and better approaches the encapsulate search,
in particular, set functions (see module Control.SetFunctions
in
package setfunctions
), which should be used.
Author: Michael Hanus
Version: July 2021
getAllValues
:: a > IO [a]
Gets all values of an expression (currently, via an incomplete depthfirst strategy). 
getSomeValue
:: a > IO a
Gets a value of an expression (currently, via an incomplete depthfirst strategy). 
allValues
:: a > [a]
Returns all values of an expression (currently, via an incomplete depthfirst strategy). 
someValue
:: a > a
Returns some value for an expression (currently, via an incomplete depthfirst strategy). 
oneValue
:: a > Maybe a
Returns just one value for an expression (currently, via an incomplete depthfirst strategy). 
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 depthfirst strategy).

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 depthfirst strategy).

oneSolution
:: Data a => (a > Bool) > Maybe a
Returns just one value satisfying a predicate. 
isFail
:: a > Bool
Does the computation of the argument to a headnormal 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. 
rewriteSome
:: a > Maybe a
Similarly to rewriteAll but returns only some value computable by term rewriting. 
Gets all values of an expression (currently, via an incomplete depthfirst 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. 
Gets a value of an expression (currently, via an incomplete depthfirst strategy). The expression must have a value, otherwise 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. 
Returns all values of an expression (currently, via an incomplete depthfirst 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.

Returns some value for an expression (currently, via an incomplete depthfirst 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.

Returns just one value for an expression (currently, via an incomplete
depthfirst strategy). If the expression has no value, 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.

Returns all values satisfying a predicate, i.e., all arguments such that
the predicate applied to the argument can be evaluated to Note that this operation is not purely declarative since the ordering of the computed values depends on the ordering of the program rules. 
Returns some value satisfying a predicate, i.e., some argument such that
the predicate applied to the argument can be evaluated to 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. 
Returns just one value satisfying a predicate.
If there is no such value, 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. 
Does the computation of the argument to a headnormal form fail? Conceptually, the argument is evaluated on a copy, i.e., even if the computation does not fail, it has not been evaluated.

Gets all values computable by term rewriting.
In contrast to

Similarly to rewriteAll
but returns only some value computable
by term rewriting. Returns
