KisaragiEffective · KisaragiEffective · Jan 11, 2025 · Jan 11, 2025
diff --git a/package/origlang-ast/src/lib.rs b/package/origlang-ast/src/lib.rs
@@ -13,14 +13,24 @@ pub struct RootAst {
     pub statement: Vec<Statement>,
 }
 
+/// 分岐を含まない任意のパターン
 #[derive(Eq, PartialEq, Clone, Debug)]
-pub enum AtomicPattern {
+pub enum SinglePattern {
     Discard,
     Bind(Identifier),
     Tuple(Vec<Self>),
+    // TODO: 定数パターンやガード付きパターンを記述できるようにする
 }
 
-impl Display for AtomicPattern {
+impl SinglePattern {
+    // 将来実装するので今は黙らせる
+    #[expect(clippy::must_use_candidate, clippy::missing_const_for_fn)]
+    pub fn is_irrefutable_with_scrutinee_type_information(&self) -> bool {
+        true
+    }
+}
+
+impl Display for SinglePattern {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         match self {
             Self::Discard => f.write_str("_"),
@@ -44,7 +54,7 @@ pub enum Statement {
         expression: Expression,
     },
     VariableDeclaration {
-        pattern: AtomicPattern,
+        pattern: SinglePattern,
         expression: Expression,
         type_annotation: Option<TypeSignature>,
     },

diff --git a/package/origlang-parser/src/parser.rs b/package/origlang-parser/src/parser.rs
@@ -1,4 +1,4 @@
-use origlang_ast::{AtomicPattern, RootAst, Statement, TypeSignature};
+use origlang_ast::{SinglePattern, RootAst, Statement, TypeSignature};
 use origlang_lexer::token::internal::DisplayToken;
 use origlang_lexer::token::Token;
 use origlang_lexer::Lexer;
@@ -911,7 +911,7 @@ impl Parser {
         }
     }
 
-    fn parse_tuple_destruct_pattern(&self) -> Result<AtomicPattern, ParserError> {
+    fn parse_tuple_destruct_pattern(&self) -> Result<SinglePattern, ParserError> {
         debug!("pattern:tuple");
         self.read_and_consume_or_report_unexpected_token(&Token::SymLeftPar)?;
 
@@ -939,10 +939,10 @@ impl Parser {
 
         self.read_and_consume_or_report_unexpected_token(&Token::SymRightPar)?;
 
-        Ok(AtomicPattern::Tuple(v))
+        Ok(SinglePattern::Tuple(v))
     }
 
-    fn parse_atomic_pattern(&self) -> Result<AtomicPattern, ParserError> {
+    fn parse_atomic_pattern(&self) -> Result<SinglePattern, ParserError> {
         debug!("pattern:atomic");
         let it = self.lexer.peek().ok_or_else(|| {
             ParserError::new(ParserErrorInner::EndOfFileError, self.lexer.last_position)
@@ -951,11 +951,11 @@ impl Parser {
         match &it.data {
             Token::Identifier { inner: name } => {
                 self.lexer.next();
-                Ok(AtomicPattern::Bind(name.clone()))
+                Ok(SinglePattern::Bind(name.clone()))
             }
             Token::SymUnderscore => {
                 self.lexer.next();
-                Ok(AtomicPattern::Discard)
+                Ok(SinglePattern::Discard)
             }
             Token::SymLeftPar => self.parse_tuple_destruct_pattern(),
             other_token => Err(Self::create_unexpected_token_error(

diff --git a/package/origlang-testsuite/src/main.rs b/package/origlang-testsuite/src/main.rs
@@ -10,7 +10,7 @@ fn main() {
 
 use log::{debug, info};
 use origlang_ast::after_parse::{BinaryOperatorKind, Expression};
-use origlang_ast::{AtomicPattern, Comment, Identifier, RootAst, Statement, TypeSignature};
+use origlang_ast::{SinglePattern, Comment, Identifier, RootAst, Statement, TypeSignature};
 use origlang_ir::IntoVerbatimSequencedIR;
 use origlang_ir_optimizer::lower::{EachStep, LowerStep, TheTranspiler};
 use origlang_ir_optimizer::preset::NoOptimization;
@@ -633,7 +633,7 @@ print a
             .expect("properly parsed")
             .statement,
             [Statement::VariableDeclaration {
-                pattern: AtomicPattern::Bind(Identifier::new("a".into())),
+                pattern: SinglePattern::Bind(Identifier::new("a".into())),
                 expression: Expression::Tuple {
                     expressions: vec![
                         Expression::IntLiteral {
@@ -764,7 +764,7 @@ print 1
         assert_eq!(
             Self::ast("var a = 1 << 2\n").expect("fail").statement,
             [Statement::VariableDeclaration {
-                pattern: AtomicPattern::Bind(Identifier::new("a".into())),
+                pattern: SinglePattern::Bind(Identifier::new("a".into())),
                 expression: Expression::BinaryOperator {
                     lhs: Box::new(Expression::IntLiteral {
                         value: 1,
@@ -788,7 +788,7 @@ print 1
         assert_eq!(
             Self::ast("var a = 4 >> 2\n").expect("fail").statement,
             [Statement::VariableDeclaration {
-                pattern: AtomicPattern::Bind(Identifier::new("a".into())),
+                pattern: SinglePattern::Bind(Identifier::new("a".into())),
                 expression: Expression::BinaryOperator {
                     lhs: Box::new(Expression::IntLiteral {
                         value: 4,

diff --git a/package/origlang-typecheck/src/type_check.rs b/package/origlang-typecheck/src/type_check.rs
@@ -2,7 +2,7 @@ pub mod error;
 
 use log::debug;
 use origlang_ast::after_parse::{BinaryOperatorKind, Expression};
-use origlang_ast::{AtomicPattern, Identifier, RootAst, Statement, TypeSignature};
+use origlang_ast::{SinglePattern, Identifier, RootAst, Statement, TypeSignature};
 use origlang_typesystem_model::{
     AssignableQueryAnswer, Type, TypedExpression, TypedIntLiteral, TypedRootAst, TypedStatement,
 };
@@ -250,12 +250,16 @@ impl TryIntoTypeCheckedForm for Expression {
 
 fn handle_atomic_pattern(
     expr: TypedExpression,
-    element_binding: &AtomicPattern,
+    element_binding: &SinglePattern,
     checker: &TypeChecker,
 ) -> Result<Vec<TypedStatement>, TypeCheckError> {
+    if !element_binding.is_irrefutable_with_scrutinee_type_information() {
+        return Err(TypeCheckError::RefutablePattern)
+    }
+
     match element_binding {
-        AtomicPattern::Discard => Ok(vec![TypedStatement::EvalAndForget { expression: expr }]),
-        AtomicPattern::Bind(identifier) => {
+        SinglePattern::Discard => Ok(vec![TypedStatement::EvalAndForget { expression: expr }]),
+        SinglePattern::Bind(identifier) => {
             checker
                 .ctx
                 .borrow_mut()
@@ -266,7 +270,7 @@ fn handle_atomic_pattern(
                 expression: expr,
             }])
         }
-        AtomicPattern::Tuple(tp) => desugar_recursive_pattern_match(tp, expr, checker),
+        SinglePattern::Tuple(tp) => desugar_recursive_pattern_match(tp, expr, checker),
     }
 }
 
@@ -276,7 +280,7 @@ enum RecursivePatternMatchDesugarStrategy {
 }
 
 fn desugar_recursive_pattern_match(
-    outer_destruction: &[AtomicPattern],
+    outer_destruction: &[SinglePattern],
     mut rhs: TypedExpression,
     checker: &TypeChecker,
 ) -> Result<Vec<TypedStatement>, TypeCheckError> {
@@ -289,7 +293,7 @@ fn desugar_recursive_pattern_match(
                 let Type::Tuple(tuple_element_types) = tp else {
                     debug!("non-tuple expression");
                     break Err(TypeCheckError::UnsatisfiablePattern {
-                        pattern: AtomicPattern::Tuple(outer_destruction.to_vec()),
+                        pattern: SinglePattern::Tuple(outer_destruction.to_vec()),
                         expression: TypedExpression::Variable {
                             ident,
                             tp: tp.clone(),
@@ -318,7 +322,7 @@ fn desugar_recursive_pattern_match(
 
                 debug!("tuple arity mismatch");
                 break Err(TypeCheckError::UnsatisfiablePattern {
-                    pattern: AtomicPattern::Tuple(outer_destruction.to_vec()),
+                    pattern: SinglePattern::Tuple(outer_destruction.to_vec()),
                     expression: TypedExpression::Variable {
                         ident,
                         tp: Type::tuple(tuple_element_types.clone()),
@@ -420,7 +424,7 @@ fn desugar_recursive_pattern_match(
             other => {
                 debug!("unsupported expression");
                 break Err(TypeCheckError::UnsatisfiablePattern {
-                    pattern: AtomicPattern::Tuple(outer_destruction.to_vec()),
+                    pattern: SinglePattern::Tuple(outer_destruction.to_vec()),
                     expr_type: other.actual_type(),
                     expression: other,
                 });
@@ -431,7 +435,7 @@ fn desugar_recursive_pattern_match(
 
 fn extract_pattern(
     expr: TypedExpression,
-    pattern: &AtomicPattern,
+    pattern: &SinglePattern,
     type_annotation: Option<TypeSignature>,
     checker: &TypeChecker,
 ) -> Result<Vec<TypedStatement>, TypeCheckError> {

diff --git a/package/origlang-typecheck/src/type_check/error.rs b/package/origlang-typecheck/src/type_check/error.rs
@@ -1,5 +1,5 @@
 use origlang_ast::after_parse::BinaryOperatorKind;
-use origlang_ast::{AtomicPattern, Identifier, TypeSignature};
+use origlang_ast::{SinglePattern, Identifier, TypeSignature};
 use origlang_typesystem_model::Type;
 use origlang_typesystem_model::TypedExpression;
 use thiserror::Error;
@@ -40,8 +40,10 @@ pub enum TypeCheckError {
     UnknownType { name: TypeSignature },
     #[error("pattern {pattern} may not be satisfied where the expression has type of {expr_type}")]
     UnsatisfiablePattern {
-        pattern: AtomicPattern,
+        pattern: SinglePattern,
         expression: TypedExpression,
         expr_type: Type,
     },
+    #[error("cannot use this pattern at here because it is not exhaustive")]
+    RefutablePattern,
 }