Change guard to DestructType

compiler/can/src/expr.rs

@@ -941,7 +941,7 @@ fn canonicalize_field<'a>(
 
     match field {
         // Both a label and a value, e.g. `{ name: "blah" }`
-        LabeledValue(label, _, loc_expr) => {
+        RequiredValue(label, _, loc_expr) => {
             let field_var = var_store.fresh();
             let (loc_can_expr, output) =
                 canonicalize_expr(env, var_store, scope, loc_expr.region, &loc_expr.value);
@@ -954,6 +954,10 @@ fn canonicalize_field<'a>(
             )
         }
 
+        OptionalValue(_, _, _) => {
+            todo!("TODO gracefully handle an optional field being used in an Expr");
+        }
+
         // A label with no value, e.g. `{ name }` (this is sugar for { name: name })
         LabelOnly(_) => {
             panic!("Somehow a LabelOnly record field was not desugared!");

compiler/can/src/pattern.rs

@@ -44,7 +44,14 @@ pub struct RecordDestruct {
     pub var: Variable,
     pub label: Lowercase,
     pub symbol: Symbol,
-    pub guard: Option<(Variable, Located<Pattern>)>,
+    pub typ: DestructType,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum DestructType {
+    Required,
+    Optional(Variable),
+    Guard(Variable, Located<Pattern>),
 }
 
 pub fn symbols_from_pattern(pattern: &Pattern) -> Vec<Symbol> {
@@ -253,7 +260,7 @@ pub fn canonicalize_pattern<'a>(
                                         var: var_store.fresh(),
                                         label: Lowercase::from(label),
                                         symbol,
-                                        guard: None,
+                                        typ: DestructType::Required,
                                     },
                                 });
                             }
@@ -271,7 +278,8 @@ pub fn canonicalize_pattern<'a>(
                             }
                         };
                     }
-                    RecordField(label, loc_guard) => {
+
+                    RequiredField(label, loc_guard) => {
                         // a guard does not introduce the label into scope!
                         let symbol = scope.ignore(label.into(), &mut env.ident_ids);
                         let can_guard = canonicalize_pattern(
@@ -289,7 +297,7 @@ pub fn canonicalize_pattern<'a>(
                                 var: var_store.fresh(),
                                 label: Lowercase::from(label),
                                 symbol,
-                                guard: Some((var_store.fresh(), can_guard)),
+                                typ: DestructType::Guard(var_store.fresh(), can_guard),
                             },
                         });
                     }
@@ -305,7 +313,8 @@ pub fn canonicalize_pattern<'a>(
                 destructs,
             })
         }
-        RecordField(_name, _loc_pattern) => {
+
+        RequiredField(_name, _loc_pattern) | OptionalField(_name, _loc_pattern) => {
             unreachable!("should have been handled in RecordDestructure");
         }
 

compiler/fmt/src/annotation.rs

@@ -248,7 +248,7 @@ impl<'a> Formattable<'a> for AssignedField<'a, TypeAnnotation<'a>> {
         indent: u16,
     ) {
         // we abuse the `Newlines` type to decide between multiline or single-line layout
-        format_assigned_field_help(self, buf, parens, indent, " : ", newlines == Newlines::Yes);
+        format_assigned_field_help(self, buf, parens, indent, " ", newlines == Newlines::Yes);
     }
 }
 
@@ -265,7 +265,7 @@ impl<'a> Formattable<'a> for AssignedField<'a, Expr<'a>> {
         indent: u16,
     ) {
         // we abuse the `Newlines` type to decide between multiline or single-line layout
-        format_assigned_field_help(self, buf, parens, indent, ": ", newlines == Newlines::Yes);
+        format_assigned_field_help(self, buf, parens, indent, "", newlines == Newlines::Yes);
     }
 }
 
@@ -273,7 +273,9 @@ fn is_multiline_assigned_field_help<'a, T: Formattable<'a>>(afield: &AssignedFie
     use self::AssignedField::*;
 
     match afield {
-        LabeledValue(_, spaces, ann) => !spaces.is_empty() || ann.value.is_multiline(),
+        RequiredValue(_, spaces, ann) | OptionalValue(_, spaces, ann) => {
+            !spaces.is_empty() || ann.value.is_multiline()
+        }
         LabelOnly(_) => false,
         AssignedField::SpaceBefore(_, _) | AssignedField::SpaceAfter(_, _) => true,
         Malformed(text) => text.chars().any(|c| c == '\n'),
@@ -285,7 +287,7 @@ fn format_assigned_field_help<'a, T>(
     buf: &mut String<'a>,
     parens: Parens,
     indent: u16,
-    separator: &str,
+    separator_prefix: &str,
     is_multiline: bool,
 ) where
     T: Formattable<'a>,
@@ -293,7 +295,7 @@ fn format_assigned_field_help<'a, T>(
     use self::AssignedField::*;
 
     match zelf {
-        LabeledValue(name, spaces, ann) => {
+        RequiredValue(name, spaces, ann) => {
             if is_multiline {
                 newline(buf, indent);
             }
@@ -304,7 +306,23 @@ fn format_assigned_field_help<'a, T>(
                 fmt_spaces(buf, spaces.iter(), indent);
             }
 
-            buf.push_str(separator);
+            buf.push_str(separator_prefix);
+            buf.push(':');
+            ann.value.format(buf, indent);
+        }
+        OptionalValue(name, spaces, ann) => {
+            if is_multiline {
+                newline(buf, indent);
+            }
+
+            buf.push_str(name.value);
+
+            if !spaces.is_empty() {
+                fmt_spaces(buf, spaces.iter(), indent);
+            }
+
+            buf.push_str(separator_prefix);
+            buf.push('?');
             ann.value.format(buf, indent);
         }
         LabelOnly(name) => {
@@ -316,10 +334,24 @@ fn format_assigned_field_help<'a, T>(
         }
         AssignedField::SpaceBefore(sub_field, spaces) => {
             fmt_comments_only(buf, spaces.iter(), indent);
-            format_assigned_field_help(sub_field, buf, parens, indent, separator, is_multiline);
+            format_assigned_field_help(
+                sub_field,
+                buf,
+                parens,
+                indent,
+                separator_prefix,
+                is_multiline,
+            );
         }
         AssignedField::SpaceAfter(sub_field, spaces) => {
-            format_assigned_field_help(sub_field, buf, parens, indent, separator, is_multiline);
+            format_assigned_field_help(
+                sub_field,
+                buf,
+                parens,
+                indent,
+                separator_prefix,
+                is_multiline,
+            );
             fmt_comments_only(buf, spaces.iter(), indent);
         }
         Malformed(raw) => {

compiler/fmt/src/pattern.rs

@@ -25,7 +25,9 @@ impl<'a> Formattable<'a> for Pattern<'a> {
             Pattern::Nested(nested_pat) => nested_pat.is_multiline(),
 
             Pattern::RecordDestructure(fields) => fields.iter().any(|f| f.is_multiline()),
-            Pattern::RecordField(_, subpattern) => subpattern.is_multiline(),
+            Pattern::RequiredField(_, subpattern) | Pattern::OptionalField(_, subpattern) => {
+                subpattern.is_multiline()
+            }
 
             Pattern::Identifier(_)
             | Pattern::GlobalTag(_)
@@ -92,12 +94,18 @@ impl<'a> Formattable<'a> for Pattern<'a> {
                 buf.push_str(" }");
             }
 
-            RecordField(name, loc_pattern) => {
+            RequiredField(name, loc_pattern) => {
                 buf.push_str(name);
                 buf.push_str(": ");
                 loc_pattern.format(buf, indent);
             }
 
+            OptionalField(name, loc_pattern) => {
+                buf.push_str(name);
+                buf.push_str(" ? ");
+                loc_pattern.format(buf, indent);
+            }
+
             NumLiteral(string) => buf.push_str(string),
             NonBase10Literal {
                 base,