Implement parsing.
Compact the grammar at every step.
Combinator conforms to Identifiable.
Style.
Character conforms to Identifiable.
Convenient construction of literals.
Tests of parsing.
Strings are Identifiable.
Alphabets are Identifiable.
HashablePairs wrap Identifiables.
Test parsing the empty string.
Bump Set for Printable support.
Define toString() for Box<T>.
Deriving defaults to Empty.
nil is implicit.
Pretty-print literals with toString().
Unpack the parameters correctly for the derivative.
Fix compaction of alternations of x with empty.
Test compaction.
Remove the old function for compaction.