Why ParquetReader/Writer is not visible without features = ["lazy","parquet"]?

[tomthestorm]

Hi,
I try to use polars lib .
When I have in Cargo.toml

[dependencies]
polars = { git = "polars_path_to_git"}

ParquetReader/Writer struct is not visible after

use polars::prelude::*;

I cannot use it:
not found in polars::prelude

but when I use :

polars = { git = "polars_path_to_git", features = ["lazy", "parquet"]}

usage ParquetReader/Write is possible .
Why ? Struct is public, no info in docs to use "features" option ?

Thanks for answer in advance.

[Michael-F-Bryan]

@tomthestorm

Why ?

This is called conditional compilation and allows a crate to only include part of its API when certain feature flags are provided. This often lets you save compilation times by not compiling the features (and dependencies!) you don't need.

@tomthestorm

Struct is public, no info in docs to use "features" option ?

This is documented.

There's section at the root of the crate's documentation listing all of the features that can be enabled.

[tomthestorm]

Thanks a lot .
Another brick in the rust wall .