Visual studio path configuration on Windows for LEAN theorem prover - visual-studio-code

Question

I am trying to set up my VS Code environment to work with LEAN the automated theorem prover.
I set up a new project following the tutorial at here and have a file called test.lean, given as follows:
import data.real.basic
I get the following error:
invalid import: data.real.basic
could not resolve import: data.real.basic
The error message suggested I call lean --path, so I did, and obtained:
PS C:\Users\user\lean_test2> lean --path
{
"is_user_leanpkg_path": false,
"leanpkg_path_file": "C:\\Users\\user\\lean_test2\\leanpkg.path",
"path": [
"C:\\Users\\user\\.elan\\toolchains\\leanprover-community--lean---3.35.1\\bin\\..\\library",
"C:\\Users\\user\\.elan\\toolchains\\leanprover-community--lean---3.35.1\\bin\\..\\lib\\lean\\library",
"C:\\Users\\user\\lean_test2\\_target/deps/mathlib/src",
"C:\\Users\\user\\lean_test2\\./src"
]
}
I noticed the paths use a mix of / and \\, but I don't think this will be a problem. I checked the third entry in the paths list, and found that the following file
C:\Users\user\lean_test2\_target\deps\mathlib\src\data\real\basic.lean
does indeed exist. So, what might be going wrong?

Answer 1

I don't know exactly what the problem is, but you should usually either use the "open folder" feature in VScode to open the folder containing mathlib or open the folder containing a project depending on mathlib. There's also a leanproject global-install command you can use to globally install mathlib without having to open a folder in VScode, but I've never used this command myself.