fix: allow var and discard with data on right hand side

crates/aiken-lang/src/ast.rs

@@ -694,14 +694,6 @@ pub enum Pattern<Constructor, Type> {
         name: String,
     },
 
-    /// A reference to a variable in a bit string. This is always a variable
-    /// being used rather than a new variable being assigned.
-    VarUsage {
-        location: Span,
-        name: String,
-        tipo: Type,
-    },
-
     /// A name given to a sub-pattern using the `as` keyword.
     /// e.g. `assert (1, [_, _] as the_list) = x`
     Assign {
@@ -747,7 +739,6 @@ impl<A, B> Pattern<A, B> {
             Pattern::Assign { pattern, .. } => pattern.location(),
             Pattern::Int { location, .. }
             | Pattern::Var { location, .. }
-            | Pattern::VarUsage { location, .. }
             | Pattern::List { location, .. }
             | Pattern::Discard { location, .. }
             | Pattern::String { location, .. }
@@ -763,6 +754,13 @@ impl<A, B> Pattern<A, B> {
     pub fn is_discard(&self) -> bool {
         matches!(self, Self::Discard { .. })
     }
+
+    /// Returns `true` if the pattern is [`Var`].
+    ///
+    /// [`Var`]: Pattern::Discard
+    pub fn is_var(&self) -> bool {
+        matches!(self, Self::Var { .. })
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Copy)]

crates/aiken-lang/src/format.rs

@@ -1458,8 +1458,6 @@ impl<'comments> Formatter<'comments> {
 
             Pattern::Var { name, .. } => name.to_doc(),
 
-            Pattern::VarUsage { name, .. } => name.to_doc(),
-
             Pattern::Assign { name, pattern, .. } => {
                 self.pattern(pattern).append(" as ").append(name.as_str())
             }

crates/aiken-lang/src/tipo/expr.rs

@@ -831,7 +831,7 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
                 Some(ann_typ),
             )?
         } else {
-            if value_typ.is_data() {
+            if value_typ.is_data() && !pattern.is_var() && !pattern.is_discard() {
                 return Err(Error::CastDataNoAnn {
                     location,
                     value: UntypedExpr::Assignment {

crates/aiken-lang/src/tipo/pattern.rs

@@ -12,7 +12,7 @@ use super::{
     environment::{assert_no_labeled_arguments, collapse_links, EntityKind, Environment},
     error::Error,
     hydrator::Hydrator,
-    PatternConstructor, Type, ValueConstructor, ValueConstructorVariant,
+    PatternConstructor, Type, ValueConstructorVariant,
 };
 use crate::{
     ast::{CallArg, Pattern, Span, TypedPattern, UntypedMultiPattern, UntypedPattern},
@@ -235,32 +235,6 @@ impl<'a, 'b> PatternTyper<'a, 'b> {
                 Ok(Pattern::Var { name, location })
             }
 
-            Pattern::VarUsage { name, location, .. } => {
-                let ValueConstructor { tipo, .. } = self
-                    .environment
-                    .get_variable(&name)
-                    .cloned()
-                    .ok_or_else(|| Error::UnknownVariable {
-                    location,
-                    name: name.to_string(),
-                    variables: self.environment.local_value_names(),
-                })?;
-
-                self.environment.increment_usage(&name);
-
-                let tipo = self
-                    .environment
-                    .instantiate(tipo, &mut HashMap::new(), self.hydrator);
-
-                self.environment.unify(int(), tipo.clone(), location)?;
-
-                Ok(Pattern::VarUsage {
-                    name,
-                    location,
-                    tipo,
-                })
-            }
-
             // Pattern::Concatenate {
             //     location,
             //     left_location,

crates/aiken-lang/src/uplc.rs

@@ -864,7 +864,6 @@ impl<'a> CodeGenerator<'a> {
                 });
                 pattern_vec.append(values);
             }
-            Pattern::VarUsage { .. } => unreachable!(),
             Pattern::Assign { name, pattern, .. } => {
                 let mut new_vec = vec![];
                 new_vec.push(Air::Let {
@@ -1034,7 +1033,6 @@ impl<'a> CodeGenerator<'a> {
             Pattern::Int { .. } => unreachable!(),
             Pattern::String { .. } => unreachable!(),
             Pattern::Var { .. } => unreachable!(),
-            Pattern::VarUsage { .. } => unreachable!(),
             Pattern::Assign { .. } => todo!("Nested assign not yet implemented"),
             Pattern::Discard { .. } => {
                 pattern_vec.push(Air::Void { scope });
@@ -1504,7 +1502,6 @@ impl<'a> CodeGenerator<'a> {
             Pattern::Assign { .. } => todo!("Nested assign is not yet done"),
             Pattern::Int { .. } => unimplemented!(),
             Pattern::String { .. } => unimplemented!(),
-            Pattern::VarUsage { .. } => unreachable!(),
         }
     }
 
@@ -1552,7 +1549,6 @@ impl<'a> CodeGenerator<'a> {
                     pattern_vec.append(&mut assert_vec);
                 }
             }
-            Pattern::VarUsage { .. } => unreachable!(),
             Pattern::Assign { .. } => todo!("Assign not yet implemented yet"),
             Pattern::Discard { .. } => {
                 pattern_vec.push(Air::Let {
@@ -1651,7 +1647,6 @@ impl<'a> CodeGenerator<'a> {
             Pattern::Int { .. } => todo!(),
             Pattern::String { .. } => todo!(),
             Pattern::Var { .. } => todo!(),
-            Pattern::VarUsage { .. } => todo!(),
             Pattern::Assign { .. } => todo!(),
             Pattern::Discard { .. } => todo!(),
             Pattern::List { elements, tail, .. } => {
@@ -1697,7 +1692,6 @@ impl<'a> CodeGenerator<'a> {
                         }
                         Pattern::Int { .. } => todo!(),
                         Pattern::String { .. } => todo!(),
-                        Pattern::VarUsage { .. } => todo!(),
                         Pattern::Assign { .. } => todo!(),
                         Pattern::Discard { .. } => {
                             names.push("_".to_string());
@@ -1846,7 +1840,6 @@ impl<'a> CodeGenerator<'a> {
 
                 self.recursive_assert_tipo(tipo, pattern_vec, name, scope);
             }
-            Pattern::VarUsage { .. } => todo!(),
             Pattern::Assign { .. } => todo!(),
             Pattern::Discard { .. } => unreachable!(),
             Pattern::List { elements, tail, .. } => {
@@ -1858,7 +1851,6 @@ impl<'a> CodeGenerator<'a> {
                         Pattern::Var { name, .. } => {
                             names.push(name.clone());
                         }
-                        Pattern::VarUsage { .. } => todo!(),
                         Pattern::Assign { .. } => todo!(),
                         l @ (Pattern::List { .. }
                         | Pattern::Constructor { .. }
@@ -2582,7 +2574,6 @@ impl<'a> CodeGenerator<'a> {
                 }
                 Pattern::Int { .. } => todo!(),
                 Pattern::String { .. } => todo!(),
-                Pattern::VarUsage { .. } => todo!(),
                 Pattern::Assign { .. } => todo!(),
             };