add error messages

Effect-TS · Sep 18, 2023 · 5854173 · 5854173
1 parent 1274746
commit 5854173
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diff --git a/.changeset/lazy-pigs-cross.md b/.changeset/lazy-pigs-cross.md
@@ -1,5 +1,5 @@
 ---
-"@effect/schema": minor
+"@effect/schema": patch
 ---
 
-Enforce explicit `Schema.Class` type parameters for better developer experience
+Enforce explicit `Schema.Class` type parameters
diff --git a/docs/modules/Schema.ts.md b/docs/modules/Schema.ts.md
@@ -999,7 +999,9 @@ Added in v1.0.0
 ```ts
 export declare const Class: <Self = never>() => <Fields extends StructFields>(
   fields: Fields
-) => Self extends never ? never : Class<Simplify<FromStruct<Fields>>, Simplify<ToStruct<Fields>>, Self, Data.Case>
+) => [Self] extends [never]
+  ? 'missing Self generic - use `class Self extends Class<Self>()({ ... })`'
+  : Class<Simplify<FromStruct<Fields>>, Simplify<ToStruct<Fields>>, Self, Data.Case>
 ```
 
 Added in v1.0.0
@@ -1016,8 +1018,8 @@ export interface Class<I, A, Self, Inherited = Data.Case> extends Schema<I, Self
 
   readonly extend: <Extended = never>() => <FieldsB extends StructFields>(
     fields: FieldsB
-  ) => Extended extends never
-    ? never
+  ) => [Extended] extends [never]
+    ? 'missing Self generic - use `class Self extends Base.extend<Self>()({ ... })`'
     : Class<
         Simplify<Omit<I, keyof FieldsB> & FromStruct<FieldsB>>,
         Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
@@ -1029,16 +1031,16 @@ export interface Class<I, A, Self, Inherited = Data.Case> extends Schema<I, Self
     fields: FieldsB,
     decode: (input: A) => ParseResult.ParseResult<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
     encode: (input: Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>) => ParseResult.ParseResult<A>
-  ) => Transformed extends never
-    ? never
+  ) => [Transformed] extends [never]
+    ? 'missing Self generic - use `class Self extends Base.transform<Self>()({ ... })`'
     : Class<I, Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>, Transformed, Self>
 
   readonly transformFrom: <Transformed = never>() => <FieldsB extends StructFields>(
     fields: FieldsB,
     decode: (input: I) => ParseResult.ParseResult<Omit<I, keyof FieldsB> & FromStruct<FieldsB>>,
     encode: (input: Simplify<Omit<I, keyof FieldsB> & FromStruct<FieldsB>>) => ParseResult.ParseResult<I>
-  ) => Transformed extends never
-    ? never
+  ) => [Transformed] extends [never]
+    ? 'missing Self generic - use `class Self extends Base.transformFrom<Self>()({ ... })`'
     : Class<I, Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>, Transformed, Self>
 }
 ```

diff --git a/src/Schema.ts b/src/Schema.ts
@@ -3355,12 +3355,14 @@ export interface Class<I, A, Self, Inherited = Data.Case> extends Schema<I, Self
 
   readonly extend: <Extended = never>() => <FieldsB extends StructFields>(
     fields: FieldsB
-  ) => Extended extends never ? never : Class<
-    Simplify<Omit<I, keyof FieldsB> & FromStruct<FieldsB>>,
-    Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
-    Extended,
-    Self
-  >
+  ) => [Extended] extends [never]
+    ? "missing Self generic - use `class Self extends Base.extend<Self>()({ ... })`"
+    : Class<
+      Simplify<Omit<I, keyof FieldsB> & FromStruct<FieldsB>>,
+      Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
+      Extended,
+      Self
+    >
 
   readonly transform: <Transformed = never>() => <
     FieldsB extends StructFields
@@ -3372,12 +3374,14 @@ export interface Class<I, A, Self, Inherited = Data.Case> extends Schema<I, Self
     encode: (
       input: Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>
     ) => ParseResult.ParseResult<A>
-  ) => Transformed extends never ? never : Class<
-    I,
-    Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
-    Transformed,
-    Self
-  >
+  ) => [Transformed] extends [never]
+    ? "missing Self generic - use `class Self extends Base.transform<Self>()({ ... })`"
+    : Class<
+      I,
+      Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
+      Transformed,
+      Self
+    >
 
   readonly transformFrom: <Transformed = never>() => <
     FieldsB extends StructFields
@@ -3389,12 +3393,14 @@ export interface Class<I, A, Self, Inherited = Data.Case> extends Schema<I, Self
     encode: (
       input: Simplify<Omit<I, keyof FieldsB> & FromStruct<FieldsB>>
     ) => ParseResult.ParseResult<I>
-  ) => Transformed extends never ? never : Class<
-    I,
-    Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
-    Transformed,
-    Self
-  >
+  ) => [Transformed] extends [never]
+    ? "missing Self generic - use `class Self extends Base.transformFrom<Self>()({ ... })`"
+    : Class<
+      I,
+      Simplify<Omit<A, keyof FieldsB> & ToStruct<FieldsB>>,
+      Transformed,
+      Self
+    >
 }
 
 /**
@@ -3404,7 +3410,7 @@ export interface Class<I, A, Self, Inherited = Data.Case> extends Schema<I, Self
 export const Class = <Self = never>() =>
 <Fields extends StructFields>(
   fields: Fields
-): Self extends never ? never
+): [Self] extends [never] ? "missing Self generic - use `class Self extends Class<Self>()({ ... })`"
   : Class<Simplify<FromStruct<Fields>>, Simplify<ToStruct<Fields>>, Self> =>
   makeClass(struct(fields), fields, Data.Class.prototype)