Allow one-element lists to be used as integers in expressions

If an operator requires an integer value but instead receives a list
value that contains a single integer, that integer will be extracted
and used instead.

1 files changed, 8 insertions, 2 deletions

diff --git a/src/types/expression_stack.rs b/src/types/expression_stack.rs
index 1036842..fdf6ed8 100644
--- a/src/types/expression_stack.rs
+++ b/src/types/expression_stack.rs
@@ -18,7 +18,10 @@ impl ExpressionStack {
             1 => {
                 match self.stack.pop().unwrap() {
                     IntermediateValue::Integer(value) => Ok(*value),
-                    IntermediateValue::List(_) => Err(ExpressionError::InvalidReturnType("a list")),
+                    IntermediateValue::List(mut list) => match list.len() {
+                        1 => Ok(list.pop().unwrap().value),
+                        _ => Err(ExpressionError::InvalidReturnType("a list")),
+                    }
                     IntermediateValue::Block(_) => Err(ExpressionError::InvalidReturnType("a block")),
                 }
             }
@@ -95,7 +98,10 @@ fn null_span() -> SourceSpan {
 fn to_isize(value: IntermediateValue) -> Result<isize, ExpressionError> {
     let received = match value {
         IntermediateValue::Integer(integer) => return Ok(integer.value),
-        IntermediateValue::List(_) => "a list",
+        IntermediateValue::List(mut list) => match list.len() {
+            1 => return Ok(list.pop().unwrap().value),
+            _ => "a list"
+        }
         IntermediateValue::Block(_) => "a block",
     };
     Err(ExpressionError::InvalidArgumentType("an integer", received))