Rust Polars feature select in Cargo.toml not working - rust

Question

I have a strange behavior. Apparently I must have messed up something:
My toml file:
[package]
name = "test"
version = "0.1.0"
edition = "2021"
[dependencies]
# Version 0.22.7 ==> works
polars = {version = "0.22.8", features = ["lazy"]}
# Version 0.23.0 ==> Does Not Work ... and it will load the 0.23.2 version?!
#polars = {version = "0.23.0", features = ["lazy"]}
Main main.cs:
use polars::prelude::*;
pub fn main() {
let path = "C:\\temp\\rusty.csv";
let days = LazyCsvReader::new(path.into())
.has_header(false)
.finish()
.unwrap()
.collect();
}
Error:
error[E0433]: failed to resolve: use of undeclared type `LazyCsvReader`
--> src\main.rs:25:16
|
25 | let days = LazyCsvReader::new(path.into())
| ^^^^^^^^^^^^^ use of undeclared type `LazyCsvReader`
Any ideas ...?
Digging further I can see that part of the feature-tree is missing in version 0.23.2 of polars:
│ ├── polars feature "csv-file"
│ │ ├── polars v0.22.8 (*)
│ │ ├── polars feature "polars-io"
│ │ │ └── polars v0.22.8 (*)
│ │ ├── polars feature "polars-lazy"
│ │ │ └── polars v0.22.8 (*)
│ │ ├── polars-io feature "csv-file" (*)
│ │ └── polars-lazy feature "csv-file"
│ │ ├── polars-lazy v0.22.7 (*)
│ │ └── polars-io feature "csv-file" (*)
==> a BUG?
Version 0.23.1 of polars is feature complete ... does not have this problem
now my workaround question is: How do I force a specific version to be part of my project?
This:
polars = {version = "0.23.1", features = ["lazy"]}
did not work ...

Answer 1

Thanks to #isaactfa we have this workaround/solution:
polars = {version = "0.23.2", features = ["lazy", "csv-file"]}
My understanding is that the "csv-file" feature is a dependency feature of "lazy" and thus should have been loaded with just the "lazy" flag.
The other workaround is to really force polars' version to "<= 0.23.1"
polars = {version = "<= 0.23.1", features = ["lazy"]}