Apparently Foreign.unsafePerformIO is not just a re-export of
System.IO.Unsafe.unsafePerformIO (or vise versa), it is a different function,
so you get an ambiguity if you import both.
showType :: Type -> String
categories :: PGF -> [Cat]
But both are implemented as quick hacks: categories is implemented by listing
all functions and taking the target categories from their types. showType uses
ppType copied & modified from PGF.Type, and needs a ppExpr, which is currently
implemented by wrapping showExpr...
TODO: need something correpsonding to PGF.categoryContext.
Some C run-time functionality is now available in the GF shell, by starting
GF with 'gf -cshell' or 'gf -crun'. Only limited functionality is available
when running the shell in these modes:
- You can only import .pgf files, not source files.
- The -retain flag can not be used and the commands that require it to work
are not available.
- Only 18 of the 40 commands available in the usual shell have been
implemented. The 'linearize' and 'parse' commands are the only ones
that call the C run-time system, and they support only a limited set of
options and flags. Use the 'help' commmands for details.
- A new command 'generate_all', that calls PGF2.generateAll, has been added.
Unfortuntaly, using it causes 'segmentation fault'.
This is implemented by adding two new modules: GF.Command.Commands2 and
GF.Interactive2. They are copied and modified versions of GF.Command.Commands
and GF.Interactive, respectively. Code for unimplemented commands and other
code that has not been adapted to the C run-time system has been left in
place, but commented out, pending further work.
The API in the C runtime as well as in the Haskell, Python and Java binding
is changed. Now instead of adding the literal callbacks to the concrete syntax
you need to supply them every time when you need to parse. The main reason is:
- referentially transparent API for Haskell
- when we start using memory mapped files we will not be allowed to change
anything in the grammar data structures. At that point the old API would
be impossible to use.
loadConcr, unloadConcr and addLiteral modify the Concr structure as a side
effect. This means that other functions with a Concr argument (e.g. parse
and linearize) are no longer pure.
Possible solutions:
1. Don't try to hide the imperative nature of the C run-time system: remove
all uses of unsafePerformIO and let all functions operate in the IO monad.
2. Don't export functions with side effects. Perhaps the desired functionality
of loadConcr, unloadConcr and addLiteral can be folded into readPGF.
The Concr structures can then treaded as immutable after after the
readPGF function returns...
