1 files changed, 4 insertions, 4 deletions
diff --git a/u/types/fn/optional.ts b/u/types/fn/optional.ts
index 3396a45..504e496 100644
--- a/u/types/fn/optional.ts
+++ b/u/types/fn/optional.ts
@@ -1,4 +1,4 @@
-import { type Mapper, type Supplier, Tagged, isTagged } from '@emprespresso/pengueno';
+import { type Mapper, Predicate, type Supplier, Tagged, isTagged } from '@emprespresso/pengueno';
 
 export type MaybeGiven<T> = T | undefined | null;
 
@@ -9,7 +9,7 @@ export class IOptionalEmptyError extends Error {}
 export interface IOptional<t, T extends NonNullable<t> = NonNullable<t>> extends Tagged<IOptionalTag>, Iterable<T> {
     readonly move: <_T>(t: MaybeGiven<_T>) => IOptional<_T>;
     readonly map: <_T>(mapper: Mapper<T, MaybeGiven<_T>>) => IOptional<_T>;
-    readonly filter: (mapper: Mapper<T, boolean>) => IOptional<T>;
+    readonly filter: (mapper: Predicate<T>) => IOptional<T>;
     readonly flatMap: <_T>(mapper: Mapper<T, MaybeGiven<IOptional<_T>>>) => IOptional<_T>;
     readonly orSome: (supplier: Supplier<MaybeGiven<t>>) => IOptional<T>;
     readonly get: Supplier<T>;
@@ -48,11 +48,11 @@ export class Optional<t, T extends NonNullable<t> = NonNullable<t>> extends _Tag
     }
 
     public get(): T {
-        if (isNone(this.self)) throw new IOptionalEmptyError('empty value');
+        if (isNone(this.self)) throw new IOptionalEmptyError('called get() on None optional');
         return this.self.value;
     }
 
-    public filter(mapper: Mapper<T, boolean>): IOptional<T> {
+    public filter(mapper: Predicate<T>): IOptional<T> {
         if (isNone(this.self) || !mapper(this.self.value)) return Optional.none();
         return Optional.some(this.self.value);
     }