1 files changed, 13 insertions, 1 deletions
diff --git a/src/prelude/array.ts b/src/prelude/array.ts
index aee17640ed..abef6ca039 100644
--- a/src/prelude/array.ts
+++ b/src/prelude/array.ts
@@ -6,6 +6,18 @@ export function count<T>(x: T, xs: T[]): number {
 	return countIf(y => x === y, xs);
 }
 
+export function concat<T>(xss: T[][]): T[] {
+	return ([] as T[]).concat(...xss);
+}
+
 export function intersperse<T>(sep: T, xs: T[]): T[] {
-	return [].concat(...xs.map(x => [sep, x])).slice(1);
+	return concat(xs.map(x => [sep, x])).slice(1);
+}
+
+export function erase<T>(x: T, xs: T[]): T[] {
+	return xs.filter(y => x !== y);
+}
+
+export function unique<T>(xs: T[]): T[] {
+	return [...new Set(xs)];
 }