feat(strings): add join() HOF

thi-ng · Mar 16, 2020 · 1c5c46f · 1c5c46f
1 parent f8c626c
commit 1c5c46f
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diff --git a/packages/strings/src/index.ts b/packages/strings/src/index.ts
@@ -6,6 +6,7 @@ export * from "./format";
 export * from "./groups";
 export * from "./hollerith";
 export * from "./interpolate";
+export * from "./join";
 export * from "./pad-left";
 export * from "./pad-right";
 export * from "./parse";

diff --git a/packages/strings/src/join.ts b/packages/strings/src/join.ts
@@ -0,0 +1,26 @@
+import { memoize1 } from "@thi.ng/memoize";
+import type { Stringer } from "./api";
+
+/**
+ * Higher-order version of `Array.join()`. Takes separator string `sep`
+ * and returns function which accepts an array and joins all elements w/
+ * separator into a result string.
+ *
+ * @example
+ * ```ts
+ * const slashes = join("/");
+ *
+ * slashes([1, 2, 3]);
+ * // "1/2/3"
+ *
+ * const formatOBJFace = partial(
+ *   format, ["f ", slashes, " ", slashes, " ", slashes]
+ * );
+ *
+ * formatOBJFace([1, 2], [3, 4], [5, 6]);
+ * // "f 1/2 3/4 5/6"
+ * ```
+ */
+export const join = memoize1<string, Stringer<any[]>>((sep) => (x) =>
+    x.join(sep)
+);