4 files changed, 62 insertions, 0 deletions
diff --git a/src/lang/util/index.ts b/src/lang/util/index.ts
new file mode 100644
index 0000000..00a3e54
--- /dev/null
+++ b/src/lang/util/index.ts
@@ -0,0 +1,3 @@
+export * from "./number";
+export * from "./utils";
+export * from "./string";
diff --git a/src/lang/util/number.ts b/src/lang/util/number.ts
new file mode 100644
index 0000000..132994b
--- /dev/null
+++ b/src/lang/util/number.ts
@@ -0,0 +1,34 @@
+export type NumberToArray<
+  Number extends number,
+  Carry extends readonly any[] = []
+> = Number extends Carry["length"]
+  ? Carry
+  : NumberToArray<Number, [...Carry, any]>;
+
+export type NumbersToArray<
+  Numbers extends readonly number[],
+  Carry extends readonly any[] = []
+> = Numbers extends [
+  infer Head extends number,
+  ...infer Tail extends readonly number[]
+]
+  ? NumbersToArray<Tail, [...Carry, ...NumberToArray<Head>]>
+  : Carry;
+
+export type AddNumbers<Numbers extends readonly number[]> =
+  NumbersToArray<Numbers> extends infer T extends readonly any[]
+    ? T["length"]
+    : never;
+
+export type MultiplyInner<
+  N extends number,
+  MS extends readonly any[],
+  Carry extends number = 0
+> = MS extends [infer Head extends number, ...infer Tail extends readonly any[]]
+  ? MultiplyInner<N, Tail, AddNumbers<[Carry, N]>>
+  : Carry;
+
+export type Multiply<M extends number, N extends number> = MultiplyInner<
+  M,
+  NumberToArray<N>
+>;
diff --git a/src/lang/util/string.ts b/src/lang/util/string.ts
new file mode 100644
index 0000000..5772f40
--- /dev/null
+++ b/src/lang/util/string.ts
@@ -0,0 +1,17 @@
+export type AddStrings<
+  Strings extends readonly string[],
+  Carry extends string = ""
+> = Strings extends [infer Head extends string, ...infer Tail extends string[]]
+  ? AddStrings<Tail, `${Carry}${Head}`>
+  : Carry;
+
+export type ToString<T, Carry extends string = ""> = T extends string | number
+  ? `${T}`
+  : T extends readonly any[]
+  ? T extends readonly [infer Head, ...infer Tail]
+    ? `${ToString<
+        Tail,
+        `${Carry extends "" ? "" : `${Carry}, `}${ToString<Head>}`
+      >}`
+    : `[${Carry}]`
+  : never;
diff --git a/src/lang/util/utils.ts b/src/lang/util/utils.ts
new file mode 100644
index 0000000..ac36ca1
--- /dev/null
+++ b/src/lang/util/utils.ts
@@ -0,0 +1,8 @@
+export type UnarrayIfOnlyHead<T extends readonly any[]> = T extends [
+  infer Head,
+  infer Next
+]
+  ? T
+  : T extends [infer Head]
+  ? Head
+  : T;