This prevents HUGE space leak and makes compiling a PGF a LOT faster
For example, an application grammar moved from taking over 50GB
of ram and taking 5 minutes (most of which is spent on garbage colelction)
to taking 1.2 seconds and using 42mb of memory
The price we pay is that the "variable #n is out of scope" error is now
lazy and will happen when we try to evaluate the term instead of
happening when the function returns and allowing the caller to chose how
to handle the error.
I don't think this should matter in practice, since it's very rare;
at least Inari has never encountered it.
This means that the -old-comp and -new-comp flags are not recognized anymore.
The only functional difference is that printnames were still normalized with
the old partial evaluator. Now that is done with the new partial evaluator.
This patch adds GF.Compile.Compute.ConcreteLazy, which replaces the Err monad
with the Identity monad. While the Err monad makes the interpreter
(hyper)strict, the Identity monad let's the interpreter inherit Haskell's
laziness. This can give big speedups: from 50s to 1s in one example,
from ~4 minutes to ~2 minutes for the RGL.
This is still experimental and might be buggy, so it is off by default.
You can turn it on by configuring with the -fcclazy flag, e.g.
cabal configure -fcclazy
Let me know if anything breaks.
