From bd5de023a1134a4fb43ead5d05084cdc11cc182e Mon Sep 17 00:00:00 2001
From: pyz4 <42039243+pyz4@users.noreply.github.com>
Date: Fri, 18 Apr 2025 16:48:59 -0400
Subject: [PATCH] feat(polars): add pow (`**`) operator for polars expressions
 (#15598)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

<!--
if this PR closes one or more issues, you can automatically link the PR
with
them by using one of the [*linking
keywords*](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword),
e.g.
- this PR should close #xxxx
- fixes #xxxx

you can also mention related issues, PRs or discussions!
-->

# Description
<!--
Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
changes.

Description of your pull request goes here. **Provide examples and/or
screenshots** if your changes affect the user experience.
-->
This PR adds the exponent operator ("**") to polars expressions.

```nushell
  > [[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select a b {c: ((polars col a) ** 2)}
  ╭───┬───┬───┬────╮
  │ # │ a │ b │ c  │
  ├───┼───┼───┼────┤
  │ 0 │ 6 │ 2 │ 36 │
  │ 1 │ 4 │ 2 │ 16 │
  │ 2 │ 2 │ 2 │  4 │
  ╰───┴───┴───┴────╯
```

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->
No breaking changes. Users are enabled to use the `**` operator in
polars expressions.

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use toolkit.nu; toolkit test stdlib"` to run the
tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->
An example in `polars select` was modified to showcase the `**`
operator.

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
-->
---
 crates/nu_plugin_polars/src/dataframe/command/data/select.rs  | 4 ++--
 .../src/dataframe/values/nu_expression/custom_value.rs        | 3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/crates/nu_plugin_polars/src/dataframe/command/data/select.rs b/crates/nu_plugin_polars/src/dataframe/command/data/select.rs
index 8c9a135f4b..6bcadb9d2b 100644
--- a/crates/nu_plugin_polars/src/dataframe/command/data/select.rs
+++ b/crates/nu_plugin_polars/src/dataframe/command/data/select.rs
@@ -72,7 +72,7 @@ impl PluginCommand for LazySelect {
             },
             Example {
                 description: "Select a column from a dataframe using a mix of expressions and record of expressions",
-                example: "[[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select a b {c: ((polars col a) * 2)}",
+                example: "[[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select a b {c: ((polars col a) ** 2)}",
                 result: Some(
                     NuDataFrame::try_from_columns(
                         vec![
@@ -84,7 +84,7 @@ impl PluginCommand for LazySelect {
                             vec![Value::test_int(2), Value::test_int(2), Value::test_int(2)]),
                             Column::new(
                             "c".to_string(),
-                            vec![Value::test_int(12), Value::test_int(8), Value::test_int(4)])
+                            vec![Value::test_int(36), Value::test_int(16), Value::test_int(4)])
                         ],
                         None,
                     )
diff --git a/crates/nu_plugin_polars/src/dataframe/values/nu_expression/custom_value.rs b/crates/nu_plugin_polars/src/dataframe/values/nu_expression/custom_value.rs
index b5a918f287..dc1db125ef 100644
--- a/crates/nu_plugin_polars/src/dataframe/values/nu_expression/custom_value.rs
+++ b/crates/nu_plugin_polars/src/dataframe/values/nu_expression/custom_value.rs
@@ -103,6 +103,9 @@ fn with_operator(
         Operator::Math(Math::FloorDivide) => {
             apply_arithmetic(plugin, engine, left, right, lhs_span, Div::div)
         }
+        Operator::Math(Math::Pow) => {
+            apply_arithmetic(plugin, engine, left, right, lhs_span, Expr::pow)
+        }
         Operator::Comparison(Comparison::Equal) => Ok(left
             .clone()
             .apply_with_expr(right.clone(), Expr::eq)