parse_expr parses Python syntax. global_dict only tells it how to handle names that are undefined, but a->b isn't valid Python syntax. So the only way to do this would be to create a transformer function that parses -> from the tokens and reorganizes it into an Implies call.
This actually probably won't be that hard, because -> is already a token recognized by the Python tokenizer (RARROW). Take a look at the existing transformers in sympy/parsing/sympy_parser.py to see how they work. I also recommend a site that I made for documentation on Python tokenize in general https://www.asmeurer.com/brown-water-python/index.html. Aaron Meurer On Fri, Jun 18, 2021 at 4:07 AM Paul Royik <distantjob...@gmail.com> wrote: > > I want to parse logic implication `p->q`. What should I add to global_dict, > so that parse_expr parsed it? > > I know, that SymPy doesn't have and Implication class. I will create it by > myself, but `global_dict = {'->': Implication}` doesn't work. > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/81e866b5-d1c7-4c1a-b762-1ecfc3cd22f0n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6KDNPFq%3DgmJQRHtQ7ZG-JnLxW9SpTaMeJduNOjzx2MV7Q%40mail.gmail.com.
