format 'unit as symbol "epsilon"

petr-fmt/src/config.rs

@@ -14,6 +14,7 @@ pub struct FormatterConfig {
     put_trailing_semis_on_let_bindings: bool,
     backup: bool,
     use_symbol_for_fn_return_type: bool,
+    use_symbol_for_unit_type: bool,
 }
 
 impl FormatterConfig {
@@ -85,12 +86,17 @@ impl FormatterConfig {
             put_trailing_semis_on_let_bindings: self.put_trailing_semis_on_let_bindings,
             backup: self.backup,
             use_symbol_for_fn_return_type: self.use_symbol_for_fn_return_type,
+            use_symbol_for_unit_type: self.use_symbol_for_unit_type,
         }
     }
 
     pub(crate) fn use_symbol_for_fn_return_type(&self) -> bool {
         self.use_symbol_for_fn_return_type
     }
+
+    pub(crate) fn use_symbol_for_unit_type(&self) -> bool {
+        self.use_symbol_for_unit_type
+    }
 }
 
 impl Default for FormatterConfig {
@@ -114,6 +120,7 @@ pub struct FormatterConfigBuilder {
     put_trailing_semis_on_let_bindings: bool,
     backup: bool,
     use_symbol_for_fn_return_type: bool,
+    use_symbol_for_unit_type: bool,
 }
 
 impl FormatterConfigBuilder {
@@ -251,6 +258,7 @@ impl FormatterConfigBuilder {
             put_trailing_semis_on_let_bindings: self.put_trailing_semis_on_let_bindings,
             backup: self.backup,
             use_symbol_for_fn_return_type: self.use_symbol_for_fn_return_type,
+            use_symbol_for_unit_type: self.use_symbol_for_unit_type,
         }
     }
 
@@ -263,6 +271,16 @@ impl FormatterConfigBuilder {
             ..self
         }
     }
+
+    pub fn use_symbol_for_unit_type(
+        self,
+        use_symbol_for_unit_type: bool,
+    ) -> Self {
+        Self {
+            use_symbol_for_unit_type,
+            ..self
+        }
+    }
 }
 
 impl Default for FormatterConfigBuilder {
@@ -282,6 +300,7 @@ impl Default for FormatterConfigBuilder {
             put_trailing_semis_on_let_bindings: false,
             backup: false,
             use_symbol_for_fn_return_type: true,
+            use_symbol_for_unit_type: true,
         }
     }
 }

petr-fmt/src/lib.rs

@@ -141,7 +141,7 @@ impl Formattable for FunctionDeclaration {
             buf.push_str("returns ");
         }
 
-        buf.push_str(&self.return_type.pretty_print(&ctx.interner, ctx.indentation()));
+        buf.push_str(&self.return_type.format(ctx).into_single_line().content);
 
         lines.push(ctx.new_line(buf));
 
@@ -170,8 +170,7 @@ impl Formattable for FunctionParameter {
         let ty_in = if ctx.config.use_set_notation_for_types() { "∈" } else { "in" };
 
         buf.push_str(&format!(" {ty_in} "));
-        let ty = self.ty.format(ctx).into_single_line().content;
-        buf.push_str(&ty);
+        buf.push_str(&self.ty.format(ctx).into_single_line().content);
 
         FormattedLines::new(vec![ctx.new_line(buf)])
     }
@@ -513,7 +512,7 @@ impl Formattable for TypeField {
         let name = ctx.interner.get(self.name.id);
         let mut buf = name.to_string();
         buf.push(' ');
-        buf.push_str(&self.ty.pretty_print(&ctx.interner, ctx.indentation()));
+        buf.push_str(&self.ty.format(ctx).into_single_line().content);
         FormattedLines::new(vec![ctx.new_line(buf)])
     }
 }
@@ -527,7 +526,13 @@ impl Formattable for Ty {
             Ty::Bool => "'bool".to_string(),
             Ty::Int => "'int".to_string(),
             Ty::String => "'string".to_string(),
-            Ty::Unit => "'unit".to_string(),
+            Ty::Unit => {
+                if ctx.config.use_symbol_for_unit_type() {
+                    "ε".to_string()
+                } else {
+                    "'unit".to_string()
+                }
+            },
             Ty::Named(name) => format!("'{}", ctx.interner.get(name.id)),
             Ty::Literal(lit) => lit.to_string(),
             Ty::Sum(tys) => format!(

petr-fmt/src/tests.rs

@@ -563,7 +563,7 @@ fn intrinsic() {
             fn string_literals() → 'string
               "This is a string literal."
 
-            fn my_func() → 'unit
+            fn my_func() → ε
               @puts(~string_literal)
         "#]],
     );
@@ -576,7 +576,7 @@ fn intrinsic_2() {
         r#"
                   fn my_func() returns 'unit @puts("hello, world!")"#,
         expect![[r#"
-            fn my_func() → 'unit
+            fn my_func() → ε
               @puts("hello, world!")
         "#]],
     );
@@ -647,3 +647,26 @@ fn sum_ty_formatting() {
     "#]],
     )
 }
+
+#[test]
+fn unit_ty_formatting() {
+    check(
+        Default::default(),
+        r#"
+        type bar = a f1 'unit f2 'unit
+
+        fn my_func(x in 'unit, y in 'unit, z in 'sum 'unit | 'unit) returns 'unit foo
+        "#,
+        expect![[r#"
+            type bar = a f1 ε f2 ε
+
+
+            fn my_func(
+              x ∈ ε,
+              y ∈ ε,
+              z ∈ 'Σ ε | ε,
+            ) → ε
+              foo
+        "#]],
+    )
+}