Parsing prefixed radix numbers

[mainrs]

I am trying to write a parser for lisp-like number representations. These are #nnRdddd where n is a digit representing the radix and d is a digit in said radix. I want the parser to first parse the radix and then for that given radix parse the string of digits dddd. However, when composing parsers, I cannot partially evaluate the radix parser first and use its result for the digit parser.

I do not really differentiate between lexer and parser. I directly parse into an AST.

What approaches can I take here?

[zesterer]

You can currently do this with the then_with combinator, but it's something that's likely going to be removed in a future version of the crate in favour of some other mechanism for customising the behaviour of future parsers based on the output of previous ones.

Alternatively, you can just parse add of the #nnRdddd with all possible digits and use try_map to do whatever manual consistency checks you want inline.

[mainrs]

Thank you very much! I forgot about then_with.