pythonparsec

Why am I getting a syntax error when using the >>= operator?

Note: I am importing the parsec library, which overloads the >>= (i.e. - __irshift()__) operator.

The following Python code:

#! /usr/bin/env python

# irshift_debug.py

from parsec import *

def id(x):
    """Identity parser."""
    return string("").result(x)

testp = digit() >>= id

print(testp.parse("5"))

yields:

$ ./irshift_debug.py
  File "./irshift_debug.py", line 9
    testp = digit() >>= id
                    ^
SyntaxError: invalid syntax

But, if I change the offending line to:

testp = digit().bind(id)

then I get:

$ ./irshift_debug.py
5

as expected.

I thought that >>= was the infix equivalent of bind(); is that incorrect?

Solution

  • It is a design mistake.

    I have turned to use >= as the operator for bind() and deprecated >>=. A new release of parsec.py has been upload to pypi.