Merge pull request #127 from matthewleon/nonempty

NonEmpty arrays

Author: garyb

bower.json

@@ -16,7 +16,7 @@
     "package.json"
   ],
   "dependencies": {
-    "purescript-foldable-traversable": "^3.0.0",
+    "purescript-foldable-traversable": "^3.3.0",
     "purescript-nonempty": "^4.0.0",
     "purescript-partial": "^1.2.0",
     "purescript-st": "^3.0.0",

src/Data/Array/NonEmpty.js

@@ -0,0 +1,77 @@
+"use strict";
+
+exports.fold1Impl = function (f) {
+  return function (xs) {
+    var acc = xs[0];
+    var len = xs.length;
+    for (var i = 1; i < len; i++) {
+      acc = f(acc)(xs[i]);
+    }
+    return acc;
+  };
+};
+
+exports.traverse1Impl = function () {
+  function Cont(fn) {
+    this.fn = fn;
+  }
+
+  var emptyList = {};
+
+  var ConsCell = function (head, tail) {
+    this.head = head;
+    this.tail = tail;
+  };
+
+  function finalCell(head) {
+    return new ConsCell(head, emptyList);
+  }
+
+  function consList(x) {
+    return function (xs) {
+      return new ConsCell(x, xs);
+    };
+  }
+
+  function listToArray(list) {
+    var arr = [];
+    var xs = list;
+    while (xs !== emptyList) {
+      arr.push(xs.head);
+      xs = xs.tail;
+    }
+    return arr;
+  }
+
+  return function (apply) {
+    return function (map) {
+      return function (f) {
+        var buildFrom = function (x, ys) {
+          return apply(map(consList)(f(x)))(ys);
+        };
+
+        var go = function (acc, currentLen, xs) {
+          if (currentLen === 0) {
+            return acc;
+          } else {
+            var last = xs[currentLen - 1];
+            return new Cont(function () {
+              var built = go(buildFrom(last, acc), currentLen - 1, xs);
+              return built;
+            });
+          }
+        };
+
+        return function (array) {
+          var acc = map(finalCell)(f(array[array.length - 1]));
+          var result = go(acc, array.length - 1, array);
+          while (result instanceof Cont) {
+            result = result.fn();
+          }
+
+          return map(listToArray)(result);
+        };
+      };
+    };
+  };
+}();