Add IntoArgment trait to pass arguments directly without wrapping them

src/argument.rs

@@ -33,3 +33,20 @@ impl Argument {
         }
     }
 }
+
+/// Converts a given type into an argument
+pub trait IntoArgument {
+    fn into_argument(self) -> Argument;
+}
+
+impl<E: IntoExpression> IntoArgument for E {
+    fn into_argument(self) -> Argument {
+        Argument::positional(self)
+    }
+}
+
+impl IntoArgument for Argument {
+    fn into_argument(self) -> Argument {
+        self
+    }
+}

src/context/mod.rs

@@ -10,7 +10,7 @@ use nu_protocol::{
 };
 
 use crate::{
-    argument::Argument,
+    argument::IntoArgument,
     error::{CrateError, CrateResult},
     utils::parse_nu_script,
     NewEmpty,
@@ -63,14 +63,14 @@ impl Context {
 
     /// Calls a function by the given name
     /// Errs if the function doesn't exist
-    pub fn call_fn<S: AsRef<str>, I: IntoIterator<Item = Argument>>(
+    pub fn call_fn<S: AsRef<str>, I: IntoIterator<Item = A>, A: IntoArgument>(
         &mut self,
         name: S,
         args: I,
     ) -> CrateResult<PipelineData> {
         let args = args
             .into_iter()
-            .map(|a: Argument| a.into_nu_argument())
+            .map(|a| a.into_argument().into_nu_argument())
             .collect::<Vec<_>>();
 
         let decl_id = self

tests/test_eval.rs

@@ -1,4 +1,4 @@
-use embed_nu::{Argument, CommandGroupConfig, Context, NewEmpty};
+use embed_nu::{CommandGroupConfig, Context, NewEmpty};
 use nu_protocol::PipelineData;
 
 #[test]
@@ -28,11 +28,10 @@ fn it_executes_functions() {
         PipelineData::empty(),
     )
     .unwrap();
-    ctx.call_fn("hello", []).unwrap();
+    ctx.call_fn("hello", [] as [String; 0]).unwrap();
     assert!(ctx.has_fn("world") == false);
 
-    let arg = Argument::positional("Hello from rust");
-    let pipeline = ctx.call_fn("echo", [arg]).unwrap();
+    let pipeline = ctx.call_fn("echo", ["Hello from Rust"]).unwrap();
     ctx.print_pipeline(pipeline).unwrap();
 }