Add nth command

src/commands/first.rs

@@ -2,8 +2,6 @@ use crate::errors::ShellError;
 use crate::parser::CommandRegistry;
 use crate::prelude::*;
 
-// TODO: "Amount remaining" wrapper
-
 pub fn first(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     let args = args.evaluate_once(registry)?;
 

src/commands/nth.rs

@@ -0,0 +1,32 @@
+use crate::errors::ShellError;
+use crate::parser::CommandRegistry;
+use crate::prelude::*;
+
+pub fn nth(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+    let args = args.evaluate_once(registry)?;
+
+    if args.len() == 0 {
+        return Err(ShellError::labeled_error(
+            "Nth requires an amount",
+            "needs amount",
+            args.name_span(),
+        ));
+    }
+
+    let amount = args.expect_nth(0)?.as_i64();
+
+    let amount = match amount {
+        Ok(o) => o,
+        Err(_) => {
+            return Err(ShellError::labeled_error(
+                "Value is not a number",
+                "expected integer",
+                args.expect_nth(0)?.span(),
+            ))
+        }
+    };
+
+    Ok(OutputStream::from_input(
+        args.input.values.skip(amount as u64).take(1),
+    ))
+}