How does it generate the python source from AST?

[alexpantyukhin]

Question mostly. How does it generate the python source from AST? Or it's not ready yet? Sorry, I can't find it.

[dbrattli]

Try unparse:

open Fable.Python.Ast
ast.unparse(ast.parse("42"))

[alexpantyukhin]

maybe this is out of scope of the current question, but I have the suggestion about getting base python typeshed. What if parse Python pyi into some json with some python tool (need to check if pytypo can do this). Then generate a F# AST basing on it.

[dbrattli]

Yes, the idea I had was to parse the .pyi using ast.parse and then convert to Python AST since it's already using unions and records. That would then be easier to translate to e.g F# AST.

[alexpantyukhin]

Correct me if wrong,pyi files contains sometimes conditions, evaluations. How much deep asp.parse should sniff? There are many modules functions like html.escape. But it also contains classes with if's depends on python version for example.

[dbrattli]

Yes, we would need to create a mini Python to F# transpiler handling if statements as needed. The idea is not to generate perfect code, but something that can be manually edited and fixed before making a PR.

[alexpantyukhin]

I have played a little bit with parsing definitions of function.
Tests with demo: https://github.com/alexpantyukhin/PythonParser/blob/master/PythonParser.Test/ParserTests.fs
Source: https://github.com/alexpantyukhin/PythonParser/blob/master/PythonParser/Parser.fs

It looks ugly for now (i'm newbie in F# yet). But It could the start for making some helptool for generating files based on pyi's. @dbrattli could you pleasecheck it out?

[dbrattli]

Very nice that you want to try and build a Python type-hint parser. I would probably use the Ast-module myself, but I currently have more than enough with the Fable2Python parser. If you could make it work, then it would be really great!