Polars upgrade 0.23 (#6303)

* more lazy expressions

* upgrade polars and correct functions

* arg-where example

* cargo clippy

* restore modified filter files

* correct string addition with str

* correct string addition with str

* correct message in test

crates/nu-command/src/dataframe/eager/columns.rs

@@ -0,0 +1,94 @@
+use super::super::values::NuDataFrame;
+use nu_protocol::{
+    ast::Call,
+    engine::{Command, EngineState, Stack},
+    Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+};
+
+#[derive(Clone)]
+pub struct ColumnsDF;
+
+impl Command for ColumnsDF {
+    fn name(&self) -> &str {
+        "columns"
+    }
+
+    fn usage(&self) -> &str {
+        "Show dataframe columns"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build(self.name())
+            .input_type(Type::Custom("dataframe".into()))
+            .output_type(Type::Any)
+            .category(Category::Custom("dataframe".into()))
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Dataframe columns",
+            example: "[[a b]; [1 2] [3 4]] | into df | columns",
+            result: Some(Value::List {
+                vals: vec![
+                    Value::String {
+                        val: "a".into(),
+                        span: Span::test_data(),
+                    },
+                    Value::String {
+                        val: "b".into(),
+                        span: Span::test_data(),
+                    },
+                ],
+                span: Span::test_data(),
+            }),
+        }]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        command(engine_state, stack, call, input)
+    }
+}
+
+#[allow(clippy::needless_collect)]
+fn command(
+    _engine_state: &EngineState,
+    _stack: &mut Stack,
+    call: &Call,
+    input: PipelineData,
+) -> Result<PipelineData, ShellError> {
+    let df = NuDataFrame::try_from_pipeline(input, call.head)?;
+
+    let names: Vec<Value> = df
+        .as_ref()
+        .get_column_names()
+        .iter()
+        .map(|v| Value::String {
+            val: v.to_string(),
+            span: call.head,
+        })
+        .collect();
+
+    let names = Value::List {
+        vals: names,
+        span: call.head,
+    };
+
+    Ok(PipelineData::Value(names, None))
+}
+
+#[cfg(test)]
+mod test {
+    use super::super::super::test_dataframe::test_dataframe;
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        test_dataframe(vec![Box::new(ColumnsDF {})])
+    }
+}

crates/nu-command/src/dataframe/eager/mod.rs

@@ -1,4 +1,5 @@
 mod append;
+mod columns;
 mod describe;
 mod drop;
 mod drop_duplicates;
@@ -26,6 +27,7 @@ mod with_column;
 use nu_protocol::engine::StateWorkingSet;
 
 pub use append::AppendDF;
+pub use columns::ColumnsDF;
 pub use describe::DescribeDF;
 pub use drop::DropDF;
 pub use drop_duplicates::DropDuplicates;
@@ -63,6 +65,7 @@ pub fn add_eager_decls(working_set: &mut StateWorkingSet) {
     // Dataframe commands
     bind_command!(
         AppendDF,
+        ColumnsDF,
         DataTypes,
         DescribeDF,
         DropDF,