An evolution engine loosely based on Biomorphs from Dawkins' The Blind Watchmaker.
The core type is Evolution, which a pointer to an instance of can be obtained
via the evolve.New(start *Genome, development func(*Genome) *Individual)
function. Once an instance e is obtained, e.Evolve(size int) can be called
to retrieve the next generation of Individuals, and then the generation's
survivor can be passed to e.Select(survivor *Individual).
The development function passed to New is in charge of taking a Genome and
developing it into an Individual, which includes both a genotype and a
phenotype. The phenotype is declared as interface{}, but would most likely be
some sort of image (as it was for Biomorphs). It is not used by Evolution in
any way; it's just for the natural selection process (selecting the Individual
returned from Evolve to pass to Select) that happens via some external
process.
Behind the scenes there is also a Reproduce function which takes a Genome
and creates a child Genome from it with exactly one random point mutation.
To complete the Biomorphs implementation, you'd need to implement development
to draw the tree-ish structures, and then create some sort of user interface
that would present the tree-ish images to the user to let them select.
The latest generation's surviving Individual is always available at e.Latest
and it's complete ancestry is in e.Ancestry. For space reasons, only the
Genomes are kept in the ancestry, but they can be developed into Individuals
if needed by using the development function at e.Development.