add spruce.ts (also inlined into Spruce.newt)

src/Web/Spruce.newt

@@ -29,8 +29,7 @@ pfunc runApp : ∀ msg model. Element → model → (update : msg → model →
         if (node) {
             parent.insertBefore(child, node);
             parent.removeChild(node);
-        }
+        } else {
-        else {
             parent.appendChild(child);
         }
         return child;
@@ -47,8 +46,7 @@ pfunc runApp : ∀ msg model. Element → model → (update : msg → model →
         let el;
         if (node instanceof Element && node.tagName.toLowerCase() == vnode.h1) {
             el = node;
-        }
+        } else {
-        else {
             el = document.createElement(vnode.h1);
         }
         // update node here

src/Web/spruce.ts

@@ -0,0 +1,119 @@
+// We're going to do the VDom thing, directly off of newt data
+
+type Attrib<Msg> =
+  | { tag: 0; h1: string; h2: string }
+  | { tag: 1; h1: string; h2: Msg }
+  | { tag: 2; h1: string; h2: (_: string) => Msg };
+
+type List<A> = { tag: 0 } | { tag: 1; h1: A; h2: List<A> };
+
+type VNode<Msg> =
+  | { tag: 0; h1: string } // TNode
+  | { tag: 1; h1: string; h2: List<Attrib<Msg>>; h3: List<VNode<Msg>> };
+
+type FancyElement<Msg> = Element & { events?: Record<string, Attrib<Msg> > };
+
+// the pfunc will have two dummy arguments in front, and I dunno no node?
+export function runapp<Model, Msg>(
+  node: Node,
+  init: Model,
+  update: (_: Msg) => (_: Model) => Model,
+  view: (_: Model) => VNode<Msg>,
+) {
+  function replace(parent: Node, node: Node | undefined, child: Node) {
+    if (node) {
+      parent.insertBefore(child, node);
+      parent.removeChild(node);
+    } else {
+      parent.appendChild(child);
+    }
+    return child;
+  }
+  // patch node, possibly returning a new node
+  function patch<Msg>(
+    parentNode: Node,
+    node: Node | undefined,
+    vnode: VNode<Msg>,
+  ): Node {
+    if (vnode.tag == 0) {
+      if (node && node.nodeType == 3) {
+        node.nodeValue = vnode.h1;
+        return node;
+      }
+      return replace(parentNode, node, document.createTextNode(vnode.h1));
+    }
+    let el: FancyElement<Msg>;
+    if (node instanceof Element && node.tagName.toLowerCase() == vnode.h1) {
+      el = node;
+    } else {
+      el = document.createElement(vnode.h1);
+    }
+    // update node here
+    let has: Record<string, boolean> = {};
+    for (let attrs = vnode.h2; attrs.tag == 1; attrs = attrs.h2) {
+      let attr = attrs.h1;
+      if (attr.tag == 0) {
+        let key = attr.h1;
+        has[key] = true;
+        if (key in el)
+          (el as any)[key] = attr.h2
+        else
+          el.setAttribute(key, attr.h2);
+      } else {
+        // onBlah
+        let key = attr.h1.slice(2).toLowerCase();
+        has[key] = true;
+        let events = el.events || (el.events = {});
+        if (!events[key]) el.addEventListener(key, listener);
+        events[key] = attr;
+      }
+    }
+    // remove attrs, not efficient..
+    for (let i = 0; i < el.attributes.length; ) {
+      let attr = el.attributes[i];
+      if (!has[attr.name]) {
+        el.removeAttribute(attr.name);
+      } else {
+        i++;
+      }
+    }
+    if (el.events) {
+      for (let key of Object.keys(el.events)) {
+        if (!has[key]) delete el.events[key];
+      }
+    }
+    let i = 0;
+    for (let kids = vnode.h3; kids.tag == 1; kids = kids.h2) {
+      patch(el, el.childNodes[i++], kids.h1);
+    }
+    while (el.childNodes[i]) el.removeChild(el.childNodes[i]);
+
+    return node == el ? node : replace(parentNode, node, el);
+  }
+  let model = init;
+  let vdom = view(model);
+  let listener = (ev: Event) => {
+    console.log('listener', ev, ev.target)
+    let target = ev.target as FancyElement<Msg>;
+    for (;;) {
+      if (!target) return
+      if (target.events?.[ev.type]) break
+      target = target.parentElement as FancyElement<Msg>;
+    }
+    if (!target.events) return;
+    const attr = target.events[ev.type]
+    if (attr.tag === 2) {
+      // probably need to pass back the event
+      // we'll want to deal with keypress, change, ...
+      let action = attr.h2(ev.target!.value)
+      model = update(action)(model);
+      console.log('UPDATE', action, '->', model);
+    } else if (attr.tag === 1) {
+      model = update(attr.h2)(model);
+      console.log('UPDATE', attr.h2, '->', model);
+    }
+    vdom = view(model);
+    node = patch(node.parentNode!, node, vdom);
+  };
+  node = patch(node.parentNode!, node, vdom);
+}