Convert single-element lists to integers when an integer is required

This allows an integer invocation with arguments to be wrapped in `[]`
square brackets so that it can be passed to another invocation as an
argument.

2 files changed, 15 insertions, 6 deletions

diff --git a/src/stages/intermediate.rs b/src/stages/intermediate.rs
index d630cc2..c5be44f 100644
--- a/src/stages/intermediate.rs
+++ b/src/stages/intermediate.rs
@@ -321,8 +321,11 @@ impl IntermediateParser {
         let result = self.parse_invocation(invocation, source)?;
         match result.value {
             IntermediateValue::Integer(integer) => {
-                let source = integer.source.clone();
-                Some(Tracked::from(integer, source))
+                Some(Tracked::from(integer, source.clone()))
+            }
+            IntermediateValue::List(mut integers) if integers.len() == 1 => {
+                let integer = integers.pop().unwrap();
+                Some(Tracked::from(integer, source.clone()))
             }
             IntermediateValue::Block(_) | IntermediateValue::List(_) => {
                 let error = IntermediateError::ExpectedInteger;
diff --git a/src/stages/semantic.rs b/src/stages/semantic.rs
index 96cf7af..f96a0c5 100644
--- a/src/stages/semantic.rs
+++ b/src/stages/semantic.rs
@@ -272,10 +272,16 @@ impl SemanticParser {
                 self.errors.push(Tracked::from(error, token.source));
                 None
             }
-            MacroDefinitionBody::List(list) => {
-                let error = SemanticError::ExpectedInteger(location);
-                self.errors.push(Tracked::from(error, list.source));
-                None
+            MacroDefinitionBody::List(list) => match list.value {
+                // Convert a one-element list to an integer.
+                ListToken::ListLiteral(mut integers) if integers.len() == 1 => {
+                    Some(integers.pop().unwrap())
+                }
+                _ => {
+                    let error = SemanticError::ExpectedInteger(location);
+                    self.errors.push(Tracked::from(error, list.source));
+                    None
+                }
             }
         }
     }