feat(random): add random-decimal (#402)

crates/nu-protocol/src/value/mod.rs

@@ -203,6 +203,17 @@ impl Value {
         }
     }
 
+    pub fn as_float(&self) -> Result<f64, ShellError> {
+        match self {
+            Value::Float { val, .. } => Ok(*val),
+            x => Err(ShellError::CantConvert(
+                "float".into(),
+                x.get_type().to_string(),
+                self.span()?,
+            )),
+        }
+    }
+
     /// Get the span for the current value
     pub fn span(&self) -> Result<Span, ShellError> {
         match self {
@@ -565,6 +576,10 @@ impl Value {
         Value::Int { val, span }
     }
 
+    pub fn float(val: f64, span: Span) -> Value {
+        Value::Float { val, span }
+    }
+
     // Only use these for test data. Span::unknown() should not be used in user data
     pub fn test_string(s: impl Into<String>) -> Value {
         Value::String {