Julia (a language focused on science/math) does it partially. For example in the editor or REPL you can just type \sqrt [tab] \alpha [tab] and it will generate

Julia (a language focused on science/math) does it partially. For example in the editor or REPL you can just type \sqrt [tab] \alpha [tab] and it will generate √α which is valid code. Most math symbols in unicode are supported and overloadable. And you can also write matrix like a table, such as [1 2 3 4 5 6 7 8 9]. And you can transform Julia expressions to LaTeX: https://github.com/korsbo/Latexify.jl https://github.com/korsbo/Latexify.jl But even they didn't go as far as being able to parse full LaTeX expressions (though you technically could with reader macros plus editor support).