Add a config variable with engine support (#332)

* Add a config variable with engine support

* Add a config variable with engine support

* Oops, cleanup

crates/nu-command/src/strings/build_string.rs

@@ -49,10 +49,13 @@ impl Command for BuildString {
         call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        let config = stack.get_config()?;
         let output = call
             .positional
             .iter()
-            .map(|expr| eval_expression(engine_state, stack, expr).map(|val| val.into_string(", ")))
+            .map(|expr| {
+                eval_expression(engine_state, stack, expr).map(|val| val.into_string(", ", &config))
+            })
             .collect::<Result<Vec<String>, ShellError>>()?;
 
         Ok(Value::String {

crates/nu-command/src/strings/str_/collect.rs

@@ -34,12 +34,14 @@ impl Command for StrCollect {
     ) -> Result<PipelineData, ShellError> {
         let separator: Option<String> = call.opt(engine_state, stack, 0)?;
 
+        let config = stack.get_config()?;
+
         // Hmm, not sure what we actually want. If you don't use debug_string, Date comes out as human readable
         // which feels funny
         #[allow(clippy::needless_collect)]
         let strings: Vec<String> = input
             .into_iter()
-            .map(|value| value.debug_string("\n"))
+            .map(|value| value.debug_string("\n", &config))
             .collect();
 
         let output = if let Some(separator) = separator {