added some list functions

src/function.js

@@ -1,6 +1,6 @@
 import { curry, curryN } from './curry.js'
 import { dispatch } from './fantasy-land.js'
-import { head, concat as iconcat, isIterable, iter, tail } from './list.js'
+import { head, concat as iterconcat, iter, tail } from './list.js'
 
 /** @import { Fn, Morphism, InferredMorphism, Predicate } from './types.js' */
 
@@ -14,7 +14,7 @@ export const id = x => x
 export const concat = dispatch(['fantasy-land/concat', 'concat'],
   (b, a) => {
     if (isIterable(a) || isIterable(b)) {
-      return iconcat(iter(a), iter(b))
+      return iterconcat(iter(a), iter(b))
     } else {
       return a.concat(b)
     }

src/list.js

@@ -1,4 +1,5 @@
 import { curry } from './curry.js'
+import { concat } from './function.js'
 import { inc } from './math.js'
 
 /**
@@ -28,7 +29,7 @@ export function* iter(value) {
  * @param {...(Iterable<T> | Iterator<T>)} iterators
  * @yields {T}
  */
-export const concat = function*(...iterators) {
+export const iterConcat = function*(...iterators) {
   for (const iter of iterators) {
     for (const item of Iterator.from(iter)) {
       yield item
@@ -112,12 +113,20 @@ export const tail = a => drop(1, a)
  */
 export const last = a => nth(length(a) - 1, a)
 
+export const append = curry(
+  /*
+   * @param {T | T[] | Iterable<T>} x 
+   * @param {T[] | Iterable<T>} xs 
+   */
+  (x, xs) => concat(xs, x)
+)
+
 export const prepend = curry(
   /**
     * @template T
-    * @param {T} x 
-    * @param {Iterable<T>} xs 
+    * @param {T | T[] | Iterable<T>} x 
+    * @param {T[] | Iterable<T>} xs 
     */
-  (x, xs) => concat([x], xs))
+  (x, xs) => concat(x, xs))
 
 

src/type.js

@@ -25,5 +25,4 @@ export const is = curry(
 export const isFn = x => type(x) === 'function'
 
 export const isArray = Array.isArray
-export const isIterable = x => x != null ? typeof x[Symbol.iterator] === 'function' : false