diff --git a/compiler/ast/src/common/array_dimensions.rs b/compiler/ast/src/common/array_dimensions.rs
index 4b661f703f..edb624c2d2 100644
--- a/compiler/ast/src/common/array_dimensions.rs
+++ b/compiler/ast/src/common/array_dimensions.rs
@@ -23,8 +23,6 @@ use std::{fmt, ops::Deref};
 /// A single array dimension.
 #[derive(Clone, Deserialize, Debug, PartialEq, Eq, Hash)]
 pub enum Dimension {
-    /// The dimension is `_`, that is unspecified and syntactically unknown.
-    Unspecified,
     /// The dimension was specified, e.g., `5` elements.
     Number(PositiveNumber),
 }
@@ -32,7 +30,6 @@ pub enum Dimension {
 impl fmt::Display for Dimension {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Self::Unspecified => write!(f, "_"),
             Self::Number(num) => write!(f, "{}", num),
         }
     }
@@ -42,7 +39,6 @@ impl Dimension {
     /// } Returns `Some(n)` unless the dimension is [`Unspecified`].
     pub fn as_specified(&self) -> Option<&PositiveNumber> {
         match self {
-            Self::Unspecified => None,
             Self::Number(n) => Some(n),
         }
     }
@@ -71,11 +67,6 @@ impl ArrayDimensions {
         Self(smallvec![dim])
     }
 
-    /// Returns true if the dimensions are not [`Unspecified`].
-    pub fn is_specified(&self) -> bool {
-        !self.contains(&Dimension::Unspecified)
-    }
-
     /// Returns `true` if there is an array dimension equal to zero.
     pub fn is_zero(&self) -> bool {
         self.iter().any(|d| d.is_zero())
@@ -96,7 +87,7 @@ impl ArrayDimensions {
     }
 }
 
-/// Custom Serializer for ArrayDimensios is required to ignore internal ArrayDimension nodes in the AST.
+/// Custom Serializer for ArrayDimensions is required to ignore internal ArrayDimension nodes in the AST.
 impl Serialize for ArrayDimensions {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -106,7 +97,6 @@ impl Serialize for ArrayDimensions {
         for dim in self.0.iter() {
             match dim {
                 Dimension::Number(num) => seq.serialize_element(&num)?,
-                Dimension::Unspecified => seq.serialize_element(&PositiveNumber { value: "0".into() })?,
             }
         }
         seq.end()
diff --git a/compiler/ast/src/input/input_value.rs b/compiler/ast/src/input/input_value.rs
index 8007a43110..c7270eb2ee 100644
--- a/compiler/ast/src/input/input_value.rs
+++ b/compiler/ast/src/input/input_value.rs
@@ -132,14 +132,10 @@ impl TryFrom<(Type, Expression)> for InputValue {
 
                 Self::Tuple(elements)
             }
-            (Type::Array(element_type, dimensions), Expression::ArrayInline(array_inline)) => {
+            (Type::Array(element_type, _dimensions), Expression::ArrayInline(array_inline)) => {
                 let mut elements = Vec::with_capacity(array_inline.elements.len());
                 let span = array_inline.span().clone();
 
-                if !dimensions.is_specified() {
-                    return Err(InputError::array_dimensions_must_be_specified(&span).into());
-                }
-
                 for element in array_inline.elements.into_iter() {
                     if let SpreadOrExpression::Expression(value_expression) = element {
                         elements.push(Self::try_from((*element_type.clone(), value_expression))?);
diff --git a/compiler/ast/src/types/type_.rs b/compiler/ast/src/types/type_.rs
index bb5c573984..2a24921690 100644
--- a/compiler/ast/src/types/type_.rs
+++ b/compiler/ast/src/types/type_.rs
@@ -89,11 +89,6 @@ impl Type {
                 let mut left_dims = left_dims.to_owned();
                 let mut right_dims = right_dims.to_owned();
 
-                // Unable to compare arrays with unspecified sizes.
-                if !left_dims.is_specified() || !right_dims.is_specified() {
-                    return false;
-                }
-
                 // Remove the first element from both dimensions.
                 let left_first = left_dims.remove_first();
                 let right_first = right_dims.remove_first();
diff --git a/compiler/parser/src/parser/type_.rs b/compiler/parser/src/parser/type_.rs
index 37470530ce..60fd73e73a 100644
--- a/compiler/parser/src/parser/type_.rs
+++ b/compiler/parser/src/parser/type_.rs
@@ -84,8 +84,6 @@ impl ParserContext<'_> {
     fn parse_array_dimension(&mut self) -> Option<Dimension> {
         if let Some((int, _)) = self.eat_int() {
             Some(Dimension::Number(int))
-        } else if self.eat(Token::Underscore).is_some() {
-            Some(Dimension::Unspecified)
         } else {
             None
         }
diff --git a/docs/grammar/README.md b/docs/grammar/README.md
index 9f10032127..26032ade6b 100644
--- a/docs/grammar/README.md
+++ b/docs/grammar/README.md
@@ -1013,7 +1013,7 @@ An array type consists of an element type
 and an indication of dimensions.
 There is either a single dimension,
 or a tuple of one or more dimensions.
-Each dimension is either a natural or is unspecified.
+Each dimension is natural.
 
 <a name="array-type"></a>
 ```abnf
diff --git a/docs/grammar/abnf-grammar.txt b/docs/grammar/abnf-grammar.txt
index b5f0993019..0e75b5ef3d 100644
--- a/docs/grammar/abnf-grammar.txt
+++ b/docs/grammar/abnf-grammar.txt
@@ -650,7 +650,7 @@ tuple-type = "(" [ type 1*( "," type ) ] ")"
 ; and an indication of dimensions.
 ; There is either a single dimension,
 ; or a tuple of one or more dimensions.
-; Each dimension is either a natural or is unspecified.
+; Each dimension is natural.
 
 array-type = "[" type ";" array-type-dimensions "]"
 
diff --git a/examples/hello-world/inputs/hello-world.in b/examples/hello-world/inputs/hello-world.in
index 684a41fbef..b62f1de0c4 100644
--- a/examples/hello-world/inputs/hello-world.in
+++ b/examples/hello-world/inputs/hello-world.in
@@ -1,6 +1,5 @@
 [main]
-a: u32 = 1;
-b: u32 = 2;
+y: bool = true;
 
 [registers]
-r0: u32 = 0;
\ No newline at end of file
+r0: bool = false;
diff --git a/examples/hello-world/src/main.leo b/examples/hello-world/src/main.leo
index f803309878..939345a239 100644
--- a/examples/hello-world/src/main.leo
+++ b/examples/hello-world/src/main.leo
@@ -1,5 +1,11 @@
 // The 'hello-world' main function.
-function main(a: u32, b: u32) -> u32 {
-    let c: u32 = a + b;
-    return c;
+type str = [char; _];
+
+function main(y: bool) -> bool {
+    let s = "abc";
+    return (first_el(s) == 'a') == y;
+}
+
+function first_el(s: str) -> char {
+    return s[0];
 }
diff --git a/leo/errors/src/compiler/compiler_errors.rs b/leo/errors/src/compiler/compiler_errors.rs
index be14c95d06..fde3ccf4bf 100644
--- a/leo/errors/src/compiler/compiler_errors.rs
+++ b/leo/errors/src/compiler/compiler_errors.rs
@@ -312,12 +312,4 @@ create_errors!(
         msg: format!("Tried to assign to static member `{}`", member),
         help: None,
     }
-
-    /// For when arrays with unspecified size are used in main.
-    @formatted
-    input_array_size_must_be_specified {
-        args: (),
-        msg: "arrays in main function input must have known size",
-        help: None,
-    }
 );
diff --git a/leo/errors/src/input/input_errors.rs b/leo/errors/src/input/input_errors.rs
index c8ebb79799..1e337d264a 100644
--- a/leo/errors/src/input/input_errors.rs
+++ b/leo/errors/src/input/input_errors.rs
@@ -46,14 +46,6 @@ create_errors!(
         help: None,
     }
 
-    /// For when [`ArrayDimensions`] are not specified.
-    @formatted
-    array_dimensions_must_be_specified {
-        args: (),
-        msg: "array dimensions must be specified",
-        help: None,
-    }
-
     /// For when array init is using spread.
     @formatted
     array_spread_is_not_allowed {