Is there any interest in a proposed mpl sequence, fold_seq, derived from mpl::fold and contained in boost-sandbox.sourceforge.net/vault/ in cppljevans/mpl/fold_seq_test.zip? This zip contains: * a test driver, fold_seq_test.cpp * a header file, fold_seq.hpp * bjam output of driver for intel * bjam output of driver for gcc. A better name for fold_seq might be cummulative_app since each element is a "partial_application" of the ForwardOp "operation" to part of the Seqence, where ForwardOp and Seqence are the arguments to fold, as described here: http://www.boost.org/libs/mpl/doc/refmanual/fold.html The reason for term "partial_application" is that it corresponds to "partial sum" described here: http://mathworld.wolfram.com/PartialSum.html Alternative names include "prefix reduction" or "scan": http://nf.apac.edu.au/training/MPIRefs/MPI_1.1/node84.html#Node84 Anyway, it seems that it's a useful extension to fold, since, as seen by the above references, the corresponding math concept occurs often. In addition, the test driver in the vault contains test_partial_product, where the value's at each element of the fold_seq correspond to elements in a cummulative product: http://mathworld.wolfram.com/CumulativeProduct.html Such a cummulative product could be used to calculate, at compile time, the strides for an instance of mult_array. Also, fold_seq could be used as a replacement for the get_side_type template class mentioned here: http://article.gmane.org/gmane.comp.lib.boost.devel/118867 and used to access the elements in a tuple, as demonstrated by the test_tuple_access function in the test driver. I'd be glad to discuss improvements or reasons why it's unneeded. TIA.