From 10bea676a8e3a7cd780087bd4fa9aefd6067b95c Mon Sep 17 00:00:00 2001
From: collin <16715212+collinc97@users.noreply.github.com>
Date: Fri, 4 Mar 2022 12:23:46 -0800
Subject: [PATCH 1/6] remove unsized arrays

---
 compiler/ast/src/common/array_dimensions.rs | 12 +-----------
 compiler/ast/src/input/input_value.rs       |  6 +-----
 compiler/ast/src/types/type_.rs             |  5 -----
 compiler/parser/src/parser/type_.rs         |  2 --
 docs/grammar/README.md                      |  2 +-
 docs/grammar/abnf-grammar.txt               |  2 +-
 examples/hello-world/inputs/hello-world.in  |  5 ++---
 examples/hello-world/src/main.leo           | 12 +++++++++---
 leo/errors/src/compiler/compiler_errors.rs  |  8 --------
 leo/errors/src/input/input_errors.rs        |  8 --------
 10 files changed, 15 insertions(+), 47 deletions(-)

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 {

From 1f7b1b57cce45673777e3a5e5195b8d62ceea3ab Mon Sep 17 00:00:00 2001
From: collin <16715212+collinc97@users.noreply.github.com>
Date: Fri, 4 Mar 2022 12:27:17 -0800
Subject: [PATCH 2/6] remove unsized array tests

---
 .../array_without_size/compare_fail.leo       |  9 --------
 .../array_without_size/definition.leo         | 11 ----------
 .../array_without_size/function_input.leo     | 13 -----------
 .../array_without_size/input/dummy.in         |  7 ------
 tests/compiler/array_without_size/length.leo  |  9 --------
 .../array_without_size/length_function.leo    | 17 --------------
 .../array_without_size/type_alias.leo         | 16 --------------
 .../array_without_size/compare_fail.leo.out   |  5 -----
 .../array_without_size/definition.leo.out     | 22 -------------------
 .../array_without_size/function_input.leo.out | 22 -------------------
 .../array_without_size/length.leo.out         | 22 -------------------
 .../length_function.leo.out                   | 22 -------------------
 .../array_without_size/type_alias.leo.out     | 22 -------------------
 13 files changed, 197 deletions(-)
 delete mode 100644 tests/compiler/array_without_size/compare_fail.leo
 delete mode 100644 tests/compiler/array_without_size/definition.leo
 delete mode 100644 tests/compiler/array_without_size/function_input.leo
 delete mode 100644 tests/compiler/array_without_size/input/dummy.in
 delete mode 100644 tests/compiler/array_without_size/length.leo
 delete mode 100644 tests/compiler/array_without_size/length_function.leo
 delete mode 100644 tests/compiler/array_without_size/type_alias.leo
 delete mode 100644 tests/expectations/compiler/compiler/array_without_size/compare_fail.leo.out
 delete mode 100644 tests/expectations/compiler/compiler/array_without_size/definition.leo.out
 delete mode 100644 tests/expectations/compiler/compiler/array_without_size/function_input.leo.out
 delete mode 100644 tests/expectations/compiler/compiler/array_without_size/length.leo.out
 delete mode 100644 tests/expectations/compiler/compiler/array_without_size/length_function.leo.out
 delete mode 100644 tests/expectations/compiler/compiler/array_without_size/type_alias.leo.out

diff --git a/tests/compiler/array_without_size/compare_fail.leo b/tests/compiler/array_without_size/compare_fail.leo
deleted file mode 100644
index 2aa1ce8360..0000000000
--- a/tests/compiler/array_without_size/compare_fail.leo
+++ /dev/null
@@ -1,9 +0,0 @@
-/*
-namespace: Compile
-expectation: Fail
-*/
-
-function main() {
-    let x: [u8; _] = [1u8,2];
-    let z: bool = x == [1u8,2,3]; // array size mismatch
-}
diff --git a/tests/compiler/array_without_size/definition.leo b/tests/compiler/array_without_size/definition.leo
deleted file mode 100644
index f6896c6f01..0000000000
--- a/tests/compiler/array_without_size/definition.leo
+++ /dev/null
@@ -1,11 +0,0 @@
-/*
-namespace: Compile
-expectation: Pass
-input_file: input/dummy.in
-*/
-
-function main(y: bool) -> bool {
-    let d: [u8; _] = [1,2,3,4];
-    return d == [1,2,3,4];
-}
-
diff --git a/tests/compiler/array_without_size/function_input.leo b/tests/compiler/array_without_size/function_input.leo
deleted file mode 100644
index 3255356367..0000000000
--- a/tests/compiler/array_without_size/function_input.leo
+++ /dev/null
@@ -1,13 +0,0 @@
-/*
-namespace: Compile
-expectation: Pass
-input_file: input/dummy.in
-*/
-
-function main(y: bool) -> bool {
-    return (first_el([1,2,3,4]) == 1) == y;
-}
-
-function first_el(arr: [u8; _]) -> u8 {
-    return arr[0];
-}
diff --git a/tests/compiler/array_without_size/input/dummy.in b/tests/compiler/array_without_size/input/dummy.in
deleted file mode 100644
index 9a0231bcd8..0000000000
--- a/tests/compiler/array_without_size/input/dummy.in
+++ /dev/null
@@ -1,7 +0,0 @@
-[main]
-y: bool = true;
-n: bool = false;
-a: [char; 11] = "hello world";
-
-[registers]
-r0: bool = false;
diff --git a/tests/compiler/array_without_size/length.leo b/tests/compiler/array_without_size/length.leo
deleted file mode 100644
index ab030aaf59..0000000000
--- a/tests/compiler/array_without_size/length.leo
+++ /dev/null
@@ -1,9 +0,0 @@
-/*
-namespace: Compile
-expectation: Pass
-input_file: input/dummy.in
-*/
-
-function main(a: [char; 11], y: bool) -> bool {
-    return y == (a.len() == 11);
-}
diff --git a/tests/compiler/array_without_size/length_function.leo b/tests/compiler/array_without_size/length_function.leo
deleted file mode 100644
index 2ec6cd7d11..0000000000
--- a/tests/compiler/array_without_size/length_function.leo
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
-namespace: Compile
-expectation: Pass
-input_file: input/dummy.in
-*/
-
-function main(y: bool) -> bool {
-    let x = 0u8;
-    for i in 0..strlen("I swear to god I had something for this") {
-        x += 1;
-    }
-    return (x == 39) == y;
-}
-
-function strlen(str: [char; _]) -> u32 {
-    return str.len();
-}
diff --git a/tests/compiler/array_without_size/type_alias.leo b/tests/compiler/array_without_size/type_alias.leo
deleted file mode 100644
index a48bb32ef6..0000000000
--- a/tests/compiler/array_without_size/type_alias.leo
+++ /dev/null
@@ -1,16 +0,0 @@
-/*
-namespace: Compile
-expectation: Pass
-input_file: input/dummy.in
-*/
-
-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/tests/expectations/compiler/compiler/array_without_size/compare_fail.leo.out b/tests/expectations/compiler/compiler/array_without_size/compare_fail.leo.out
deleted file mode 100644
index f3e1a96589..0000000000
--- a/tests/expectations/compiler/compiler/array_without_size/compare_fail.leo.out
+++ /dev/null
@@ -1,5 +0,0 @@
----
-namespace: Compile
-expectation: Fail
-outputs:
-  - "Error [ECMP0376093]: array sizes must match for comparison; left: 2, right: 3\n    --> compiler-test:5:19\n     |\n   5 |     let z: bool = x == [1u8,2,3]; // array size mismatch\n     |                   ^^^^^^^^^^^^^^"
diff --git a/tests/expectations/compiler/compiler/array_without_size/definition.leo.out b/tests/expectations/compiler/compiler/array_without_size/definition.leo.out
deleted file mode 100644
index 4a45516d68..0000000000
--- a/tests/expectations/compiler/compiler/array_without_size/definition.leo.out
+++ /dev/null
@@ -1,22 +0,0 @@
----
-namespace: Compile
-expectation: Pass
-outputs:
-  - circuit:
-      num_public_variables: 0
-      num_private_variables: 1
-      num_constraints: 1
-      at: 042610d0fd1fe6d6ac112138f8755752f44c7d2a00f1b5960574d6da5cda393f
-      bt: e97756698880ab7555a959a5fb5c6b4e15bd64612aa677adbfe2d0bd91f0a83c
-      ct: cf1cbb66a638b4860a516671fb74850e6ccf787fe6c4c8d29e9c04efe880bd05
-    output:
-      - input_file: input/dummy.in
-        output:
-          registers:
-            r0:
-              type: bool
-              value: "true"
-    initial_ast: 71e25416f4a31045a847f29df48d5e9cce19d0df31c479761f2387eca4bb759f
-    imports_resolved_ast: a408ca2965d8d63856b1f95385746d5be9825b646e7f97a5fd3203638681292c
-    canonicalized_ast: a408ca2965d8d63856b1f95385746d5be9825b646e7f97a5fd3203638681292c
-    type_inferenced_ast: 88e5b982b094f07cc0337812b4965b655c020bdebfa1ad7ac8fd2ddd3c730b8b
diff --git a/tests/expectations/compiler/compiler/array_without_size/function_input.leo.out b/tests/expectations/compiler/compiler/array_without_size/function_input.leo.out
deleted file mode 100644
index 6e0432d6a0..0000000000
--- a/tests/expectations/compiler/compiler/array_without_size/function_input.leo.out
+++ /dev/null
@@ -1,22 +0,0 @@
----
-namespace: Compile
-expectation: Pass
-outputs:
-  - circuit:
-      num_public_variables: 0
-      num_private_variables: 1
-      num_constraints: 1
-      at: 042610d0fd1fe6d6ac112138f8755752f44c7d2a00f1b5960574d6da5cda393f
-      bt: e97756698880ab7555a959a5fb5c6b4e15bd64612aa677adbfe2d0bd91f0a83c
-      ct: cf1cbb66a638b4860a516671fb74850e6ccf787fe6c4c8d29e9c04efe880bd05
-    output:
-      - input_file: input/dummy.in
-        output:
-          registers:
-            r0:
-              type: bool
-              value: "true"
-    initial_ast: d6d3ebe6a0b7f19e51d245d715706122577777a8325459df7db2c08ee5f841bd
-    imports_resolved_ast: 675c0542777db276ce7a39decb9dc5aacfde6b00ebfeb3982c480ed531a79be5
-    canonicalized_ast: 675c0542777db276ce7a39decb9dc5aacfde6b00ebfeb3982c480ed531a79be5
-    type_inferenced_ast: ae8cbfc3938971fc0e42fa400b1277d288ea4b7d4d8149b452fce81ae4813315
diff --git a/tests/expectations/compiler/compiler/array_without_size/length.leo.out b/tests/expectations/compiler/compiler/array_without_size/length.leo.out
deleted file mode 100644
index c0831088ad..0000000000
--- a/tests/expectations/compiler/compiler/array_without_size/length.leo.out
+++ /dev/null
@@ -1,22 +0,0 @@
----
-namespace: Compile
-expectation: Pass
-outputs:
-  - circuit:
-      num_public_variables: 0
-      num_private_variables: 12
-      num_constraints: 1
-      at: 336f487fe39f24aef980deaaf7d6dddcc0dbfa8f121c3470b05546c1ac13f87e
-      bt: ae35381db5558456a49acb22132b4930efd53b90eb2668df06c5d9c1a6b0ab9f
-      ct: cf1cbb66a638b4860a516671fb74850e6ccf787fe6c4c8d29e9c04efe880bd05
-    output:
-      - input_file: input/dummy.in
-        output:
-          registers:
-            r0:
-              type: bool
-              value: "true"
-    initial_ast: be4b4279f79a35306e1edf5086275a2b216e9d46d66b9bb5fbf650062b7cd263
-    imports_resolved_ast: c4aae9410df8034a7744ec5f1998454bacde915ddaadfab42181528f1923f742
-    canonicalized_ast: c4aae9410df8034a7744ec5f1998454bacde915ddaadfab42181528f1923f742
-    type_inferenced_ast: 0f8434f9e0430dc238602c0479a928be87101566dc0e9ae60ab9f4f1339ef313
diff --git a/tests/expectations/compiler/compiler/array_without_size/length_function.leo.out b/tests/expectations/compiler/compiler/array_without_size/length_function.leo.out
deleted file mode 100644
index 676ef0cfef..0000000000
--- a/tests/expectations/compiler/compiler/array_without_size/length_function.leo.out
+++ /dev/null
@@ -1,22 +0,0 @@
----
-namespace: Compile
-expectation: Pass
-outputs:
-  - circuit:
-      num_public_variables: 0
-      num_private_variables: 1
-      num_constraints: 1
-      at: 042610d0fd1fe6d6ac112138f8755752f44c7d2a00f1b5960574d6da5cda393f
-      bt: e97756698880ab7555a959a5fb5c6b4e15bd64612aa677adbfe2d0bd91f0a83c
-      ct: cf1cbb66a638b4860a516671fb74850e6ccf787fe6c4c8d29e9c04efe880bd05
-    output:
-      - input_file: input/dummy.in
-        output:
-          registers:
-            r0:
-              type: bool
-              value: "true"
-    initial_ast: cb9419739db39f806ff96983f53aa085a96238833ed754293042724dd3b29704
-    imports_resolved_ast: 675a67a8dae0a33a273d74ec021df0e23c5ed7cb32faf8efd2d2f087979de039
-    canonicalized_ast: b75d02c7cadbcd2906ad0d7b6376bbdc32ff1f26348913e2b0a84ced7496a2f6
-    type_inferenced_ast: 87ee95068efb0a58e18f2e3b8668db8d2ad9826b21e8b8ce6bc26f60c9fe88ca
diff --git a/tests/expectations/compiler/compiler/array_without_size/type_alias.leo.out b/tests/expectations/compiler/compiler/array_without_size/type_alias.leo.out
deleted file mode 100644
index 26b0fda988..0000000000
--- a/tests/expectations/compiler/compiler/array_without_size/type_alias.leo.out
+++ /dev/null
@@ -1,22 +0,0 @@
----
-namespace: Compile
-expectation: Pass
-outputs:
-  - circuit:
-      num_public_variables: 0
-      num_private_variables: 4
-      num_constraints: 5
-      at: e2c343f33b3c986318d821645015951a2f3fb198915bbf602e2c3e58ebfb9c73
-      bt: 71744948a918814d3008831b4b73101a5cf7346e6ff62d98968eb8b3b91aa343
-      ct: 94757fb2316d68d18fd26e96a2992b03a8db8d49d802b34201dce6f12518676b
-    output:
-      - input_file: input/dummy.in
-        output:
-          registers:
-            r0:
-              type: bool
-              value: "true"
-    initial_ast: 712ed2b7c1ddf180a39cd1bf83c7a4ca3de909a14f87250ec445ba6ae6aa6597
-    imports_resolved_ast: 36d9e14cf42065047dc21a5c68f45d3264dc0d38eb53355d3f9fef7bd7d512b1
-    canonicalized_ast: f1edababa6847e2ca24a0786bc1a0b2e66f0d60f5b11c59a24c8b1503f893092
-    type_inferenced_ast: c979556f787eb3190b0c4cec3d5a6baabbf64d32f7e3281c784f83262da33205

From 1a45295372bf312647aa4ffec66b73ba64108875 Mon Sep 17 00:00:00 2001
From: collin <16715212+collinc97@users.noreply.github.com>
Date: Fri, 4 Mar 2022 13:06:22 -0800
Subject: [PATCH 3/6] remove redundant array dimension struct

---
 compiler/ast/src/common/array_dimensions.rs | 43 +++-----------------
 compiler/ast/src/input/input_value.rs       | 44 ++++++++++-----------
 compiler/parser/src/parser/type_.rs         | 13 +-----
 3 files changed, 28 insertions(+), 72 deletions(-)

diff --git a/compiler/ast/src/common/array_dimensions.rs b/compiler/ast/src/common/array_dimensions.rs
index edb624c2d2..af5f879930 100644
--- a/compiler/ast/src/common/array_dimensions.rs
+++ b/compiler/ast/src/common/array_dimensions.rs
@@ -20,41 +20,12 @@ use serde::{ser::SerializeSeq, Deserialize, Serialize, Serializer};
 use smallvec::{smallvec, SmallVec};
 use std::{fmt, ops::Deref};
 
-/// A single array dimension.
-#[derive(Clone, Deserialize, Debug, PartialEq, Eq, Hash)]
-pub enum Dimension {
-    /// The dimension was specified, e.g., `5` elements.
-    Number(PositiveNumber),
-}
-
-impl fmt::Display for Dimension {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            Self::Number(num) => write!(f, "{}", num),
-        }
-    }
-}
-
-impl Dimension {
-    /// } Returns `Some(n)` unless the dimension is [`Unspecified`].
-    pub fn as_specified(&self) -> Option<&PositiveNumber> {
-        match self {
-            Self::Number(n) => Some(n),
-        }
-    }
-
-    /// Returns true if the dimension is known to be zero.
-    fn is_zero(&self) -> bool {
-        self.as_specified().filter(|n| n.is_zero()).is_some()
-    }
-}
-
 /// Specifies array dimensions for array [`Type`]s or in array initializer [`Expression`]s.
 #[derive(Clone, Deserialize, Debug, PartialEq, Eq, Hash)]
-pub struct ArrayDimensions(pub SmallVec<[Dimension; 1]>);
+pub struct ArrayDimensions(pub SmallVec<[PositiveNumber; 1]>);
 
 impl Deref for ArrayDimensions {
-    type Target = [Dimension];
+    type Target = [PositiveNumber];
 
     fn deref(&self) -> &Self::Target {
         &*self.0
@@ -63,7 +34,7 @@ impl Deref for ArrayDimensions {
 
 impl ArrayDimensions {
     /// Returns a single-dimensional array dimension.
-    pub fn single(dim: Dimension) -> Self {
+    pub fn single(dim: PositiveNumber) -> Self {
         Self(smallvec![dim])
     }
 
@@ -73,7 +44,7 @@ impl ArrayDimensions {
     }
 
     /// Attempts to remove the first dimension from the array, or returns `None` if it doesn't.
-    pub fn remove_first(&mut self) -> Option<Dimension> {
+    pub fn remove_first(&mut self) -> Option<PositiveNumber> {
         if self.is_empty() {
             None
         } else {
@@ -82,7 +53,7 @@ impl ArrayDimensions {
     }
 
     /// Attempts to remove the last dimension from the array, or returns `None` if it doesn't.
-    pub fn remove_last(&mut self) -> Option<Dimension> {
+    pub fn remove_last(&mut self) -> Option<PositiveNumber> {
         self.0.pop()
     }
 }
@@ -95,9 +66,7 @@ impl Serialize for ArrayDimensions {
     {
         let mut seq = serializer.serialize_seq(Some(self.0.len()))?;
         for dim in self.0.iter() {
-            match dim {
-                Dimension::Number(num) => seq.serialize_element(&num)?,
-            }
+            seq.serialize_element(&dim)?;
         }
         seq.end()
     }
diff --git a/compiler/ast/src/input/input_value.rs b/compiler/ast/src/input/input_value.rs
index c7270eb2ee..9ca0a286d0 100644
--- a/compiler/ast/src/input/input_value.rs
+++ b/compiler/ast/src/input/input_value.rs
@@ -88,32 +88,28 @@ impl TryFrom<(Type, Expression)> for InputValue {
                 }
 
                 if let Some(dimension) = array_init.dimensions.remove_first() {
-                    if let Some(number) = dimension.as_specified() {
-                        let size = number.value.parse::<usize>().unwrap();
-                        let mut values = Vec::with_capacity(size);
+                    let size = dimension.value.parse::<usize>().unwrap();
+                    let mut values = Vec::with_capacity(size);
 
-                        // For when Dimensions are specified in a canonical way: [[u8; 3], 2];
-                        // Else treat as math notation: [u8; (2, 3)];
-                        if array_init.dimensions.len() == 0 {
-                            for _ in 0..size {
-                                values.push(InputValue::try_from((*type_.clone(), *array_init.element.clone()))?);
-                            }
-                        // Faking canonical array init is relatively easy: instead of using a straightforward
-                        // recursion, with each iteration we manually modify ArrayInitExpression cutting off
-                        // dimension by dimension.
-                        } else {
-                            for _ in 0..size {
-                                values.push(InputValue::try_from((
-                                    Type::Array(type_.clone(), array_init.dimensions.clone()),
-                                    Expression::ArrayInit(array_init.clone()),
-                                ))?);
-                            }
-                        };
-
-                        Self::Array(values)
+                    // For when Dimensions are specified in a canonical way: [[u8; 3], 2];
+                    // Else treat as math notation: [u8; (2, 3)];
+                    if array_init.dimensions.len() == 0 {
+                        for _ in 0..size {
+                            values.push(InputValue::try_from((*type_.clone(), *array_init.element.clone()))?);
+                        }
+                    // Faking canonical array init is relatively easy: instead of using a straightforward
+                    // recursion, with each iteration we manually modify ArrayInitExpression cutting off
+                    // dimension by dimension.
                     } else {
-                        unreachable!("dimensions must be specified");
-                    }
+                        for _ in 0..size {
+                            values.push(InputValue::try_from((
+                                Type::Array(type_.clone(), array_init.dimensions.clone()),
+                                Expression::ArrayInit(array_init.clone()),
+                            ))?);
+                        }
+                    };
+
+                    Self::Array(values)
                 } else {
                     unreachable!("dimensions are checked for zero");
                 }
diff --git a/compiler/parser/src/parser/type_.rs b/compiler/parser/src/parser/type_.rs
index 60fd73e73a..f634fee8ed 100644
--- a/compiler/parser/src/parser/type_.rs
+++ b/compiler/parser/src/parser/type_.rs
@@ -59,12 +59,12 @@ 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() {
+        Ok(if let Some((dim, _)) = self.eat_int() {
             ArrayDimensions(smallvec![dim])
         } else {
             let mut had_item_err = false;
             let (dims, _, span) = self.parse_paren_comma_list(|p| {
-                Ok(if let Some(dim) = p.parse_array_dimension() {
+                Ok(if let Some((dim, _)) = p.eat_int() {
                     Some(dim)
                 } else {
                     let token = p.expect_any()?;
@@ -80,15 +80,6 @@ impl ParserContext<'_> {
         })
     }
 
-    /// Parses a basic array dimension, i.e., an integer or `_`.
-    fn parse_array_dimension(&mut self) -> Option<Dimension> {
-        if let Some((int, _)) = self.eat_int() {
-            Some(Dimension::Number(int))
-        } else {
-            None
-        }
-    }
-
     /// Returns a [`(Type, Span)`] tuple of AST nodes if the next token represents a type.
     /// Also returns the span of the parsed token.
     pub fn parse_type(&mut self) -> Result<(Type, Span)> {

From c30df925ef48d079aeab7df47e6ae6fc0a4dd3d6 Mon Sep 17 00:00:00 2001
From: Alessandro Coglio <coglio@kestrel.edu>
Date: Fri, 4 Mar 2022 19:42:42 -0800
Subject: [PATCH 4/6] [ABNF] Adapt ABNF to removal of unsized arrays.

This "merges" the two previous slightly different notions of array type
dimensions and array expression dimension(s) into one notion of array
dimensions, in which the dimensions have to be natural numbers. (Previously,
array type dimensions were allowed to be unspecified (via underscores), while
array expression dimensions had to be specified.)
---
 docs/grammar/abnf-grammar.txt | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/docs/grammar/abnf-grammar.txt b/docs/grammar/abnf-grammar.txt
index 0e75b5ef3d..057c4cb5d9 100644
--- a/docs/grammar/abnf-grammar.txt
+++ b/docs/grammar/abnf-grammar.txt
@@ -650,15 +650,11 @@ 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 natural.
+; Each dimension is a natural.
 
-array-type = "[" type ";" array-type-dimensions "]"
+array-type = "[" type ";" array-dimensions "]"
 
-array-type-dimension = natural / "_"
-
-array-type-dimensions = array-type-dimension
-                      / "(" array-type-dimension
-                            *( "," array-type-dimension ) [","] ")"
+array-dimensions = natural / "(" natural *( "," natural ) ")"
 
 ; The keyword `Self` denotes the enclosing circuit type.
 ; It is only allowed inside a circuit type declaration.
@@ -756,10 +752,7 @@ array-inline-construction = "["
 
 array-inline-element = expression / "..." expression
 
-array-repeat-construction = "[" expression ";" array-expression-dimensions "]"
-
-array-expression-dimensions = natural
-                            / "(" natural *( "," natural ) ")"
+array-repeat-construction = "[" expression ";" array-dimensions "]"
 
 array-construction = array-inline-construction / array-repeat-construction
 

From 6aca970b88da9f7f45ad7c38e400d62ae82f55f7 Mon Sep 17 00:00:00 2001
From: Alessandro Coglio <coglio@kestrel.edu>
Date: Fri, 4 Mar 2022 19:51:14 -0800
Subject: [PATCH 5/6] [ABNF] Re-generate markdown.

(Forgot to do this in the previous commit.)
---
 docs/grammar/README.md | 33 +++++++--------------------------
 1 file changed, 7 insertions(+), 26 deletions(-)

diff --git a/docs/grammar/README.md b/docs/grammar/README.md
index 26032ade6b..063df6180e 100644
--- a/docs/grammar/README.md
+++ b/docs/grammar/README.md
@@ -1013,34 +1013,24 @@ 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 natural.
+Each dimension is a natural.
 
 <a name="array-type"></a>
 ```abnf
-array-type = "[" type ";" array-type-dimensions "]"
+array-type = "[" type ";" array-dimensions "]"
 ```
 
-Go to: _[array-type-dimensions](#user-content-array-type-dimensions), [type](#user-content-type)_;
+Go to: _[array-dimensions](#user-content-array-dimensions), [type](#user-content-type)_;
 
 
-<a name="array-type-dimension"></a>
+<a name="array-dimensions"></a>
 ```abnf
-array-type-dimension = natural / "_"
+array-dimensions = natural / "(" natural *( "," natural ) ")"
 ```
 
 Go to: _[natural](#user-content-natural)_;
 
 
-<a name="array-type-dimensions"></a>
-```abnf
-array-type-dimensions = array-type-dimension
-                      / "(" array-type-dimension
-                            *( "," array-type-dimension ) [","] ")"
-```
-
-Go to: _[array-type-dimension](#user-content-array-type-dimension)_;
-
-
 The keyword `Self` denotes the enclosing circuit type.
 It is only allowed inside a circuit type declaration.
 
@@ -1214,19 +1204,10 @@ Go to: _[expression](#user-content-expression)_;
 
 <a name="array-repeat-construction"></a>
 ```abnf
-array-repeat-construction = "[" expression ";" array-expression-dimensions "]"
+array-repeat-construction = "[" expression ";" array-dimensions "]"
 ```
 
-Go to: _[array-expression-dimensions](#user-content-array-expression-dimensions), [expression](#user-content-expression)_;
-
-
-<a name="array-expression-dimensions"></a>
-```abnf
-array-expression-dimensions = natural
-                            / "(" natural *( "," natural ) ")"
-```
-
-Go to: _[natural](#user-content-natural)_;
+Go to: _[array-dimensions](#user-content-array-dimensions), [expression](#user-content-expression)_;
 
 
 <a name="array-construction"></a>

From 6a33035257cc09ac8ff7ce3d0ad6e4256a1450e4 Mon Sep 17 00:00:00 2001
From: collin <16715212+collinc97@users.noreply.github.com>
Date: Mon, 7 Mar 2022 14:50:53 -0800
Subject: [PATCH 6/6] remove unsized array parser tests

---
 .../functions/param_array_unsized.leo.out     | 68 -------------------
 .../parser/statement/definition.leo.out       | 47 -------------
 .../parser/functions/param_array_unsized.leo  |  8 ---
 tests/parser/statement/definition.leo         |  3 -
 4 files changed, 126 deletions(-)
 delete mode 100644 tests/expectations/parser/parser/functions/param_array_unsized.leo.out
 delete mode 100644 tests/parser/functions/param_array_unsized.leo

diff --git a/tests/expectations/parser/parser/functions/param_array_unsized.leo.out b/tests/expectations/parser/parser/functions/param_array_unsized.leo.out
deleted file mode 100644
index 41594cf508..0000000000
--- a/tests/expectations/parser/parser/functions/param_array_unsized.leo.out
+++ /dev/null
@@ -1,68 +0,0 @@
----
-namespace: Parse
-expectation: Pass
-outputs:
-  - name: ""
-    expected_input: []
-    import_statements: []
-    imports: {}
-    aliases: {}
-    circuits: {}
-    global_consts: {}
-    functions:
-      "{\"name\":\"x\",\"span\":\"{\\\"line_start\\\":3,\\\"line_stop\\\":3,\\\"col_start\\\":10,\\\"col_stop\\\":11,\\\"path\\\":\\\"\\\",\\\"content\\\":\\\"function x(x: [u8; _]) {\\\"}\"}":
-        annotations: {}
-        identifier: "{\"name\":\"x\",\"span\":\"{\\\"line_start\\\":3,\\\"line_stop\\\":3,\\\"col_start\\\":10,\\\"col_stop\\\":11,\\\"path\\\":\\\"\\\",\\\"content\\\":\\\"function x(x: [u8; _]) {\\\"}\"}"
-        input:
-          - Variable:
-              identifier: "{\"name\":\"x\",\"span\":\"{\\\"line_start\\\":3,\\\"line_stop\\\":3,\\\"col_start\\\":12,\\\"col_stop\\\":13,\\\"path\\\":\\\"\\\",\\\"content\\\":\\\"function x(x: [u8; _]) {\\\"}\"}"
-              const_: false
-              mutable: true
-              type_:
-                Array:
-                  - IntegerType: U8
-                  - - value: "0"
-              span:
-                line_start: 3
-                line_stop: 3
-                col_start: 12
-                col_stop: 13
-                path: ""
-                content: "function x(x: [u8; _]) {"
-        const_: false
-        output: ~
-        core_mapping: ~
-        block:
-          statements:
-            - Return:
-                expression:
-                  TupleInit:
-                    elements: []
-                    span:
-                      line_start: 4
-                      line_stop: 4
-                      col_start: 12
-                      col_stop: 14
-                      path: ""
-                      content: "    return ();"
-                span:
-                  line_start: 4
-                  line_stop: 4
-                  col_start: 5
-                  col_stop: 14
-                  path: ""
-                  content: "    return ();"
-          span:
-            line_start: 3
-            line_stop: 5
-            col_start: 24
-            col_stop: 2
-            path: ""
-            content: "function x(x: [u8; _]) {\n     ...\n}"
-        span:
-          line_start: 3
-          line_stop: 5
-          col_start: 1
-          col_stop: 2
-          path: ""
-          content: "function x(x: [u8; _]) {\n     ...\n}"
diff --git a/tests/expectations/parser/parser/statement/definition.leo.out b/tests/expectations/parser/parser/statement/definition.leo.out
index 21a9a0351c..359dc7bffe 100644
--- a/tests/expectations/parser/parser/statement/definition.leo.out
+++ b/tests/expectations/parser/parser/statement/definition.leo.out
@@ -1513,53 +1513,6 @@ outputs:
         col_stop: 14
         path: ""
         content: "let (x,) = ();"
-  - Definition:
-      declaration_type: Let
-      variable_names:
-        - mutable: true
-          identifier: "{\"name\":\"x\",\"span\":\"{\\\"line_start\\\":1,\\\"line_stop\\\":1,\\\"col_start\\\":5,\\\"col_stop\\\":6,\\\"path\\\":\\\"\\\",\\\"content\\\":\\\"let x: [char; _] = \\\\\\\"Hello, World!\\\\\\\";\\\"}\"}"
-          span:
-            line_start: 1
-            line_stop: 1
-            col_start: 5
-            col_stop: 6
-            path: ""
-            content: "let x: [char; _] = \"Hello, World!\";"
-      parened: false
-      type_:
-        Array:
-          - Char
-          - - value: "0"
-      value:
-        Value:
-          String:
-            - - Scalar: 72
-              - Scalar: 101
-              - Scalar: 108
-              - Scalar: 108
-              - Scalar: 111
-              - Scalar: 44
-              - Scalar: 32
-              - Scalar: 87
-              - Scalar: 111
-              - Scalar: 114
-              - Scalar: 108
-              - Scalar: 100
-              - Scalar: 33
-            - span:
-                line_start: 1
-                line_stop: 1
-                col_start: 20
-                col_stop: 35
-                path: ""
-                content: "let x: [char; _] = \"Hello, World!\";"
-      span:
-        line_start: 1
-        line_stop: 1
-        col_start: 1
-        col_stop: 35
-        path: ""
-        content: "let x: [char; _] = \"Hello, World!\";"
   - Definition:
       declaration_type: Let
       variable_names:
diff --git a/tests/parser/functions/param_array_unsized.leo b/tests/parser/functions/param_array_unsized.leo
deleted file mode 100644
index ef657ba76d..0000000000
--- a/tests/parser/functions/param_array_unsized.leo
+++ /dev/null
@@ -1,8 +0,0 @@
-/*
-namespace: Parse
-expectation: Pass
-*/
-
-function x(x: [u8; _]) {
-    return ();
-}
diff --git a/tests/parser/statement/definition.leo b/tests/parser/statement/definition.leo
index 507dca476c..ff3b33ede3 100644
--- a/tests/parser/statement/definition.leo
+++ b/tests/parser/statement/definition.leo
@@ -99,7 +99,4 @@ let (x,y,) = ();
 
 let (x,) = ();
 
-
-let x: [char; _] = "Hello, World!";
-
 let x: [[u8; 2]; 2] = [[0,0], [0,0]];