The circumflex "^" is used to concatenate two directives.
In the cases where splitting occurs, track is called on each of the split photons and the returned event lists must be concatenated.
Clearly, loops can be concatenated, provided that they have a common interval.
The first rule of the grammar concatenates equilateral triangles.
Next, these words can be concatenated together by functors.
These "type-letters" can be concatenated into words by using the type product.
In the first two cases, merging is done simply by making recursive calls to concatenate the sequences for the subterms.
It is in virtue of this that pattern contexts and substitutions can be simply concatenated.
