Switch to monorepo setup

packages/lib/Fluent.ts

@@ -0,0 +1,65 @@
+import {last} from './Tools'
+
+export class Fluent<T> {
+  constructor(readonly xs: T[]) {}
+
+  static create() {
+    return this.from([])
+  }
+
+  static from<T>(xs: Iterable<T>) {
+    return new Fluent<T>(Array.from(xs))
+  }
+
+  clone<K extends Fluent<T>>(this: K, xs: T[]): K {
+    return new (this.constructor as { new (xs: T[]): K })(xs)
+  }
+
+  valueOf = () => this.xs
+
+  first = () => this.xs[0]
+
+  nth = (i: number) => this.xs[i]
+
+  last = () => last(this.xs)
+
+  count = () => this.xs.length
+
+  exists = () => this.xs.length > 0
+
+  has = (v: T) => this.xs.includes(v)
+
+  every = (f: (t: T) => boolean) => this.xs.every(f)
+
+  some = (f: (t: T) => boolean) => this.xs.some(f)
+
+  find = (f: (t: T) => boolean) => this.xs.find(f)
+
+  uniq = () => this.clone(Array.from(new Set(this.xs)))
+
+  slice = (a: number, b?: number) => this.clone(this.xs.slice(a, b))
+
+  take = (n: number) => this.slice(0, n)
+
+  drop = (n: number) => this.slice(n)
+
+  filter = (f: (t: T) => boolean) => this.clone(this.xs.filter(f))
+
+  reject = (f: (t: T) => boolean) => this.clone(this.xs.filter(t => !f(t)))
+
+  map = (f: (t: T) => T) => this.clone(this.xs.map(f))
+
+  mapTo = <U>(f: (t: T) => U) => Fluent.from(this.xs.map(f))
+
+  flatMap = <U>(f: (t: T) => U[]) => Fluent.from(this.xs.flatMap(f))
+
+  forEach = (f: (t: T, i: number) => void) => this.xs.forEach(f)
+
+  set = (i: number, x: T) => this.clone([...this.xs.slice(0, i), x, ...this.xs.slice(i + 1)])
+
+  concat = (xs: T[]) => this.clone(this.xs.concat(xs))
+
+  append = (x: T) => this.concat([x])
+
+  prepend = (x: T) => this.clone([x].concat(this.xs))
+}