fix: export generic types from IDL module (#1099)

* fix: export generic types from IDL module

* docs: add jsdocs and update changelog

Author: ilbertt

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+- fix: export the `GenericIdlFuncArgs`, `GenericIdlFuncRets`, and `GenericIdlServiceFields` types from `@dfinity/candid`.
+
 ## [3.2.0] - 2025-08-07
 
 - fix: do not subtract the replica permitted clock drift when calculating the ingress expiry.

packages/candid/src/idl.ts

@@ -1684,8 +1684,15 @@ export class PrincipalClass extends PrimitiveType<PrincipalId> {
   }
 }
 
-type GenericFuncArgs = [Type, ...Type[]] | [];
-type GenericFuncRets = [Type, ...Type[]] | [];
+/**
+ * The generic type of the arguments of an {@link Func|IDL Function}.
+ */
+export type GenericIdlFuncArgs = [Type, ...Type[]] | [];
+
+/**
+ * The generic type of the return values of an {@link Func|IDL Function}.
+ */
+export type GenericIdlFuncRets = [Type, ...Type[]] | [];
 
 /**
  * Represents an IDL function reference.
@@ -1694,8 +1701,8 @@ type GenericFuncRets = [Type, ...Type[]] | [];
  * @param annotations Function annotations.
  */
 export class FuncClass<
-  Args extends GenericFuncArgs = GenericFuncArgs,
-  Rets extends GenericFuncRets = GenericFuncRets,
+  Args extends GenericIdlFuncArgs = GenericIdlFuncArgs,
+  Rets extends GenericIdlFuncRets = GenericIdlFuncRets,
 > extends ConstructType<[PrincipalId, string]> {
   get typeName() {
     return IdlTypeName.FuncClass;
@@ -1806,11 +1813,14 @@ export class FuncClass<
   }
 }
 
-type GenericServiceFields = Record<string, FuncClass>;
+/**
+ * The generic type of the fields of an {@link Service|IDL Service}.
+ */
+export type GenericIdlServiceFields = Record<string, FuncClass>;
 
 export class ServiceClass<
   K extends string = string,
-  Fields extends GenericServiceFields = GenericServiceFields,
+  Fields extends GenericIdlServiceFields = GenericIdlServiceFields,
 > extends ConstructType<PrincipalId> {
   get typeName() {
     return IdlTypeName.ServiceClass;
@@ -2327,8 +2337,8 @@ export function Rec(): RecClass {
  * @returns new FuncClass
  */
 export function Func<
-  Args extends GenericFuncArgs = GenericFuncArgs,
-  Ret extends GenericFuncRets = GenericFuncRets,
+  Args extends GenericIdlFuncArgs = GenericIdlFuncArgs,
+  Ret extends GenericIdlFuncRets = GenericIdlFuncRets,
 >(args: Args, ret: Ret, annotations: string[] = []): FuncClass<Args, Ret> {
   return new FuncClass(args, ret, annotations);
 }
@@ -2340,7 +2350,7 @@ export function Func<
  */
 export function Service<
   K extends string = string,
-  Fields extends GenericServiceFields = GenericServiceFields,
+  Fields extends GenericIdlServiceFields = GenericIdlServiceFields,
 >(t: Fields): ServiceClass<K, Fields> {
   return new ServiceClass(t);
 }

packages/candid/src/index.ts

@@ -1,6 +1,11 @@
 export * from './candid-ui.ts';
 export * from './candid-core.ts';
 export * as IDL from './idl.ts';
+export {
+  type GenericIdlFuncArgs,
+  type GenericIdlFuncRets,
+  type GenericIdlServiceFields,
+} from './idl.ts';
 export * from './utils/hash.ts';
 export * from './utils/leb128.ts';
 export * from './utils/buffer.ts';