Compose breaks down quite fast, two many recursions

[Sebastian Jordan]

First of all: I really like parsec. It is solid work, but I encountered a problem. I really don't know what one can do about that in python but (at least on my machine) one can only compose ~200 parsers. I used python 3.6.2.

#!/usr/bin/env python

import parsec

n = 198

p = parsec.string('')
for x in range(0,n):
    p = p.compose(parsec.string('a'))
print(p.parse('a' * n))

gives

...
  File "/nix/store/fikb92d9was1qg3h4lwnay70i2ayzzd4-python3.6-parsec-3.3/lib/python3.6/site-packages/parsec/__init__.py", line 57, in success
    return Value(True, index, actual, None)
RecursionError: maximum recursion depth exceeded while calling a Python object

[Tao He]

Thanks for your report. I will check it as soon as possible.

[Tao He]

I think the only for your problem is to increase the system's recursion limit, using sys.setrecursionlimit. You even will encounter the same problem in a trivial hand-written recursive decent parser when you stack the same parser (call the same function recursively) so many times.

The default recursion depth limit is 1000 and it is too small for specific applications.