This output format converts a GF grammar to a "canonical" GF grammar. A
canonical GF grammar consists of
- one self-contained module for the abstract syntax
- one self-contained module per concrete syntax
The concrete syntax modules contain param, lincat and lin definitions,
everything else has been eliminated by the partial evaluator, including
references to resource library modules and functors. Record types
and tables are retained.
The -output-format canonical_gf option writes canonical GF grammars to a
subdirectory "canonical/". The canonical GF grammars are written as
normal GF ".gf" source files, which can be compiled with GF in the normal way.
The translation to canonical form goes via an AST for canonical GF grammars,
defined in GF.Grammar.Canonical. This is a simple, self-contained format that
doesn't cover everyting in GF (e.g. omitting dependent types and HOAS), but it
is complete enough to translate the Foods and Phrasebook grammars found in
gf-contrib. The AST is based on the GF grammar "GFCanonical" presented here:
https://github.com/GrammaticalFramework/gf-core/issues/30#issuecomment-453556553
The translation of concrete syntax to canonical form is based on the
previously existing translation of concrete syntax to Haskell, implemented
in module GF.Compile.ConcreteToHaskell. This module could now be reimplemented
and simplified significantly by going via the canonical format. Perhaps exports
to other output formats could benefit by going via the canonical format too.
There is also the possibility of completing the GFCanonical grammar
mentioned above and using GF itself to convert canonical GF grammars to
other formats...
The def rules are now compiled to byte code by the compiler and then to
native code by the JIT compiler in the runtime. Not all constructions
are implemented yet. The partial implementation is now in the repository
but it is not activated by default since this requires changes in the
PGF format. I will enable it only after it is complete.
The old type was [String] -> String. This function was only used
in GF.Text.Lexing.stringOp, which now uses (unwords . bindTok) instead,
with no change in behaviour.
The capitalization of the first word was done in GF.Text.Lexing.stringOp,
but is now done in the functions unlexText and unlexMixed in PGF.Lexing.
These functions are only used in stringOp and in PGFService (where the change
is needed), so the subtle change in behaviour should not cause any bugs.
1. The default encoding is changed from Latin-1 to UTF-8.
2. Alternate encodings should be specified as "--# -coding=enc", the old
"flags coding=enc" declarations have no effect but are still checked for
consistency.
3. A transitional warning is generated for files that contain non-ASCII
characters without specifying a character encoding:
"Warning: default encoding has changed from Latin-1 to UTF-8"
4. Conversion to Unicode is now done *before* lexing. This makes it possible
to allow arbitrary Unicode characters in identifiers. But identifiers are
still stored as ByteStrings, so they are limited to Latin-1 characters
for now.
5. Lexer.hs is no longer part of the repository. We now generate the lexer
from Lexer.x with alex>=3. Some workarounds for bugs in alex-3.0 were
needed. These bugs might already be fixed in newer versions of alex, but
we should be compatible with what is shipped in the Haskell Platform.
