mondo: add & sugar

packages/mondo/mondo.mjs

@@ -22,6 +22,7 @@ export class MondoParser {
     number: /^-?[0-9]*\.?[0-9]+/, // before pipe!
     // TODO: better error handling when "-" is used as rest, e.g "s [- bd]"
     op: /^[*/:!@%?+-]|^\.{2}/, // * / : ! @ % ? ..
+    and: /^&/,
     // dollar: /^\$/,
     pipe: /^#/,
     stack: /^[,$]/,
@@ -150,6 +151,27 @@ export class MondoParser {
     }
     return children;
   }
+  desugar_ands(children) {
+    while (true) {
+      let opIndex = children.findIndex((child) => child.type === 'and');
+      if (opIndex === -1) break;
+      if (opIndex === children.length - 1) {
+        throw new Error(`cannot use & as last child.`);
+      }
+      if (opIndex === 0) {
+        throw new Error(`cannot use & as first child.`);
+      }
+      // convert infix to prefix notation
+      const op = { type: 'plain', value: children[opIndex].value };
+      const left = children[opIndex - 1];
+      const right = children[opIndex + 1];
+      const call = { type: 'list', children: [op, left, right] };
+      // insert call while keeping other siblings
+      children = [...children.slice(0, opIndex - 1), call, ...children.slice(opIndex + 2)];
+      children = this.unwrap_children(children);
+    }
+    return children;
+  }
   desugar_ops(children) {
     while (true) {
       let opIndex = children.findIndex((child) => child.type === 'op');
@@ -264,6 +286,7 @@ export class MondoParser {
           children = [{ type: 'plain', value: type }, ...children];
         }
         children = this.desugar_ops(children);
+        children = this.desugar_ands(children);
         // children = this.desugar_pipes(children, (children) => this.desugar_dollars(children));
         children = this.desugar_pipes(children);
         return children;

packages/mondo/test/mondo.test.mjs

@@ -117,6 +117,7 @@ describe('mondo sugar', () => {
   it('should desugar x:y', () => expect(desguar('x:y')).toEqual('(: y x)'));
   it('should desugar x:y:z', () => expect(desguar('x:y:z')).toEqual('(: z (: y x))'));
   it('should desugar x:y*x', () => expect(desguar('bd:0*2')).toEqual('(* 2 (: 0 bd))'));
+  it('should desugar x&y:z', () => expect(desguar('bd&3:8')).toEqual('(& bd (: 8 3))'));
   it('should desugar a..b', () => expect(desguar('0..2')).toEqual('(.. 2 0)'));
   /* it('should desugar x $ y', () => expect(desguar('x $ y')).toEqual('(x y)'));
   it('should desugar x $ y z', () => expect(desguar('x $ y z')).toEqual('(x (y z))'));