Test parsing literals.
Easier testing with Optionals.
Test literal parse trees.
Test unmatched input.
Test exact input.
Add a concatenation operator.
Section the tests.
Concatenation.
Add a workspace.
Add Either.
Add Box, Either, and Prelude to the workspace.
Link against Box, Either, and Prelude.
Test concatenation parse trees.
Extract the concatenation parser.
Test that concatenation parses completely.
Style: No parens.
Better documentation of the precedence of ++.
Link the tests against the dependencies.
Assert Equality over Either.

This had to be unpacked a bit, unfortunately.
Alternation.