Metamorphisms are an approach to structured recursion.
This package is currently a reorganization and slight adaptation of the original
code which was written more than a decade ago (in 1999); it is, however
quite a direct and clever way to investigate the concepts involved.
The original code and paper can be found here:
http://web.engr.oregonstate.edu/~erwig/meta/
This code uses unusual layout (in particular, I use very wide
columns and lots of spacing) in hopes that it makes the symmetry
of the functions manifest. Any mistakes in the code are almost surely
mine, and not the original author's.
Future updates should include:
documentation
an abstract syntax graph version of the included functions
diagrams of involved structures
examples demonstrated by doctest
switch to hierarchical naming
switch to available versions of components (SimpleMap, Heap)
a more general license