Mathsqrt (#3239)

* Output error when ls into a file without permission

* math sqrt

* added test to check fails when ls into prohibited dir

* fix lint

* math sqrt with tests and doc

* trigger wasm build

* Update filesystem_shell.rs

* always forgetting the linting

* fix clippy complaining

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>

crates/nu-command/src/commands.rs

@@ -218,7 +218,8 @@ pub(crate) use lines::Lines;
 pub(crate) use ls::Ls;
 pub(crate) use math::{
     Math, MathAbs, MathAverage, MathCeil, MathEval, MathFloor, MathMaximum, MathMedian,
-    MathMinimum, MathMode, MathProduct, MathRound, MathStddev, MathSummation, MathVariance,
+    MathMinimum, MathMode, MathProduct, MathRound, MathSqrt, MathStddev, MathSummation,
+    MathVariance,
 };
 pub(crate) use merge::Merge;
 pub(crate) use mkdir::Mkdir;

crates/nu-command/src/commands/default_context.rs

@@ -188,6 +188,7 @@ pub fn create_default_context(interactive: bool) -> Result<EvaluationContext, Bo
             whole_stream_command(MathRound),
             whole_stream_command(MathFloor),
             whole_stream_command(MathCeil),
+            whole_stream_command(MathSqrt),
             // File format output
             whole_stream_command(To),
             whole_stream_command(ToCsv),

crates/nu-command/src/commands/math/mod.rs

@@ -10,6 +10,7 @@ pub mod min;
 pub mod mode;
 pub mod product;
 pub mod round;
+pub mod sqrt;
 pub mod stddev;
 pub mod sum;
 pub mod variance;
@@ -29,6 +30,7 @@ pub use min::SubCommand as MathMinimum;
 pub use mode::SubCommand as MathMode;
 pub use product::SubCommand as MathProduct;
 pub use round::SubCommand as MathRound;
+pub use sqrt::SubCommand as MathSqrt;
 pub use stddev::SubCommand as MathStddev;
 pub use sum::SubCommand as MathSummation;
 pub use variance::SubCommand as MathVariance;

crates/nu-command/src/commands/math/sqrt.rs

@@ -0,0 +1,75 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{Primitive, Signature, UntaggedValue, Value};
+
+pub struct SubCommand;
+
+#[async_trait]
+impl WholeStreamCommand for SubCommand {
+    fn name(&self) -> &str {
+        "math sqrt"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("math sqrt")
+    }
+
+    fn usage(&self) -> &str {
+        "Applies the square root function to a list of numbers"
+    }
+
+    async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        operate(args).await
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Apply the square root function to a list of numbers",
+            example: "echo [9 16] | math sqrt",
+            result: Some(vec![
+                UntaggedValue::int(3).into(),
+                UntaggedValue::int(4).into(),
+            ]),
+        }]
+    }
+}
+
+async fn operate(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let mapped = args.input.map(move |val| match val.value {
+        UntaggedValue::Primitive(Primitive::Int(val)) => sqrt_big_decimal(BigDecimal::from(val)),
+        UntaggedValue::Primitive(Primitive::Decimal(val)) => sqrt_big_decimal(val),
+        other => sqrt_default(other),
+    });
+    Ok(OutputStream::from_input(mapped))
+}
+
+fn sqrt_big_decimal(val: BigDecimal) -> Value {
+    let squared = val.sqrt();
+    match squared {
+        None => UntaggedValue::Error(ShellError::unexpected("Cant square root a negative number"))
+            .into(),
+        Some(val) if !val.is_integer() => UntaggedValue::decimal(val.normalized()).into(),
+        Some(val) => UntaggedValue::int(val.with_scale(0).as_bigint_and_exponent().0).into(),
+    }
+}
+
+fn sqrt_default(_: UntaggedValue) -> Value {
+    UntaggedValue::Error(ShellError::unexpected(
+        "Only numerical values are supported",
+    ))
+    .into()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::ShellError;
+    use super::SubCommand;
+
+    #[test]
+    fn examples_work_as_expected() -> Result<(), ShellError> {
+        use crate::examples::test as test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

crates/nu-command/tests/commands/math/mod.rs

@@ -2,6 +2,7 @@ mod avg;
 mod eval;
 mod median;
 mod round;
+mod sqrt;
 mod sum;
 
 use nu_test_support::{nu, pipeline};

crates/nu-command/tests/commands/math/sqrt.rs

@@ -0,0 +1,31 @@
+use nu_test_support::nu;
+
+#[test]
+fn can_sqrt_numbers() {
+    let actual = nu!(
+        cwd: ".",
+        "echo [0.25 2 4] | math sqrt | math sum"
+    );
+
+    assert_eq!(actual.out, "3.914213562373095048801688724209698078569671875376948073176679737990732478462107038850387534327641573");
+}
+
+#[test]
+fn can_sqrt_irrational() {
+    let actual = nu!(
+        cwd: ".",
+        "echo 2 | math sqrt"
+    );
+
+    assert_eq!(actual.out, "1.414213562373095048801688724209698078569671875376948073176679737990732478462107038850387534327641573");
+}
+
+#[test]
+fn can_sqrt_perfect_square() {
+    let actual = nu!(
+        cwd: ".",
+        "echo 4 | math sqrt"
+    );
+
+    assert_eq!(actual.out, "2");
+}

docs/commands/math.md

@@ -13,6 +13,7 @@ Currently the following functions are implemented:
 * `math min`: Finds the minimum within a list of numbers or tables
 * `math mode`: Finds the most frequent element(s) within a list of numbers or tables
 * `math round`: Applies the round function to a list of numbers
+* `math sqrt`: Applies the square root function to a list of numbers
 * `math stddev`: Finds the standard deviation of a list of numbers or tables
 * `math sum`: Finds the sum of a list of numbers or tables
 * `math product`: Finds the product of a list of numbers or tables
@@ -148,6 +149,15 @@ To get the average of the file sizes in a directory, simply pipe the size column
 ───┴────
 ```
 
+```shell
+> echo [4 16 0.25] | math sqrt
+───┬────
+ 0 │  2
+ 1 │  4
+ 2 │  0.5
+───┴────
+```
+
 ```shell
 > echo [1 -2 -3.0] | math abs
 ───┬────────