private IEnumerable <Expression> DistinctFor(
IEnumerable <Expression> elements, int minPartitions,
Func <Partition <Expression>, IEnumerable <Expression> > partitionExpressionBuilder,
Func <Expression, IEnumerable <Expression>, IEnumerable <Expression>, IEnumerable <Expression> > reduceExpressionBuilder) =>
elements.Take(2).Count() == 1 ? elements
: Partitionings.Of(elements)
.All()
.Where(partitioning => partitioning.Count() >= minPartitions)
.SelectMany(partitioning => partitioning.Select(partitionExpressionBuilder).CrossProduct())
.SelectMany(subexpressions =>
this.ThreeWaySplit(subexpressions)
.SelectMany(split => reduceExpressionBuilder(split.head, split.direct, split.inverse)));
static void PartitioningDemo() =>
InputNumberSequences
.SelectMany(numbers => Partitionings.Of(numbers).All())
.Select(partitioning => partitioning.Select(partition => string.Join(" ", partition.ToArray())))
.Select(partitions => string.Join(" | ", partitions))
.WriteLinesTo(Console.Out);