diff --git a/Cargo.lock b/Cargo.lock
index ea45669892..c8a5345bd7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1538,6 +1538,7 @@ dependencies = [
  "serde",
  "serde_json",
  "serde_yaml",
+ "smallvec",
  "tendril",
  "tracing",
 ]
diff --git a/parser/Cargo.toml b/parser/Cargo.toml
index e16765ebcf..e96457c567 100644
--- a/parser/Cargo.toml
+++ b/parser/Cargo.toml
@@ -23,6 +23,9 @@ name = "leo_ast"
 path = "benches/leo_ast.rs"
 harness = false
 
+[dependencies]
+smallvec = "1.8"
+
 [dependencies.leo-ast]
 path = "../ast"
 version = "1.5.3"
diff --git a/parser/src/parser/expression.rs b/parser/src/parser/expression.rs
index 79c6e020d0..137e171ac3 100644
--- a/parser/src/parser/expression.rs
+++ b/parser/src/parser/expression.rs
@@ -403,7 +403,7 @@ impl ParserContext<'_> {
     /// circuit initialization expression.
     pub fn parse_circuit_expression(&mut self, identifier: Identifier) -> Result<Expression> {
         let (members, _, span) = self.parse_list(Token::LeftCurly, Token::RightCurly, Token::Comma, |p| {
-            Ok(Some(CircuitImpliedVariableDefinition {
+            Ok(Some(CircuitVariableInitializer {
                 identifier: p.expect_ident()?,
                 expression: p.eat(Token::Colon).map(|_| p.parse_expression()).transpose()?,
             }))
diff --git a/parser/src/parser/file.rs b/parser/src/parser/file.rs
index 7902ed5807..4e740a3fba 100644
--- a/parser/src/parser/file.rs
+++ b/parser/src/parser/file.rs
@@ -559,19 +559,12 @@ impl ParserContext<'_> {
     /// const definition statement and assignment.
     ///
     pub fn parse_type_alias(&mut self) -> Result<(Identifier, Alias)> {
-        self.expect(Token::Type)?;
+        let start = self.expect(Token::Type)?;
         let name = self.expect_ident()?;
         self.expect(Token::Assign)?;
-        let (type_, _) = self.parse_type()?;
-        self.expect(Token::Semicolon)?;
+        let (represents, _) = self.parse_type()?;
+        let span = start + self.expect(Token::Semicolon)?;
 
-        Ok((
-            name.clone(),
-            Alias {
-                represents: type_,
-                span: name.span.clone(),
-                name,
-            },
-        ))
+        Ok((name.clone(), Alias { represents, span, name }))
     }
 }
diff --git a/parser/src/parser/type_.rs b/parser/src/parser/type_.rs
index 9c73c00a21..37470530ce 100644
--- a/parser/src/parser/type_.rs
+++ b/parser/src/parser/type_.rs
@@ -17,6 +17,8 @@
 use super::*;
 use leo_errors::{ParserError, Result};
 
+use smallvec::smallvec;
+
 pub(crate) const TYPE_TOKENS: &[Token] = &[
     Token::I8,
     Token::I16,
@@ -58,7 +60,7 @@ impl ParserContext<'_> {
     /// Returns an [`ArrayDimensions`] AST node if the next tokens represent dimensions for an array type.
     pub fn parse_array_dimensions(&mut self) -> Result<ArrayDimensions> {
         Ok(if let Some(dim) = self.parse_array_dimension() {
-            dim
+            ArrayDimensions(smallvec![dim])
         } else {
             let mut had_item_err = false;
             let (dims, _, span) = self.parse_paren_comma_list(|p| {
@@ -74,16 +76,16 @@ impl ParserContext<'_> {
             if dims.is_empty() && !had_item_err {
                 self.emit_err(ParserError::array_tuple_dimensions_empty(&span));
             }
-            ArrayDimensions::Multi(dims)
+            ArrayDimensions(dims.into())
         })
     }
 
     /// Parses a basic array dimension, i.e., an integer or `_`.
-    fn parse_array_dimension(&mut self) -> Option<ArrayDimensions> {
+    fn parse_array_dimension(&mut self) -> Option<Dimension> {
         if let Some((int, _)) = self.eat_int() {
-            Some(ArrayDimensions::Number(int))
+            Some(Dimension::Number(int))
         } else if self.eat(Token::Underscore).is_some() {
-            Some(ArrayDimensions::Unspecified)
+            Some(Dimension::Unspecified)
         } else {
             None
         }