Replace '??' with 'al'

ref #283

documentation/intermediate-dsl.md

@@ -423,7 +423,7 @@ In `foo() lest bar() lest baz()` execution proceeds from left to right until an
 | ------------------ | ------------- | ------ |
 | Logical AND        | `2 and 0`     | `0`    |
 | Logical OR         | `0 or 2`      | `2`    |
-| Nullish coalescing | `niente ?? 2` | `2`    |
+| Niente coalescing  | `niente al 2` | `2`    |
 
 Logical operators check for *truthiness*. The falsy values are `false`, `niente`, `0`, `""` and `[]` while everything else is truthy. Note that this means that `0.0` representing zero cents or `1/1` as a linear frequency ratio is truthy.
 
@@ -436,8 +436,8 @@ Coalescing operators short-circuit. Execution stops once the value of the expres
 false or print('This executes too')
 true  or print("This won't execute")
 
-niente ?? print('This executes as well')
-0      ?? print("This won't execute")
+niente al print('This executes as well')
+0      al print("This won't execute")
 ```
 
 #### Array

documentation/technical.md

@@ -49,7 +49,7 @@ All operations are left-associative except exponentiation, recipropower, and log
 | `==`, `<>`, `~=`, `<=`, `>=`, `<`, `>`, `of`, `not of`, `~of`, `not ~of`, `in`, `not in`, `~in`, `not ~in` | Strict equality, size equality, comparisons, strict/non-strict value inclusion, strict/non-strict index/key inclusion |
 | `not x`, `vnot x`                                | Boolean not, vector not                                                 |
 | `and`, `vand`                                    | Boolean and, vector and                                                 |
-| `or`, `vor`, `??`                                | Boolean or, vector or, niente coalescing                                |
+| `or`, `vor`, `al`                                | Boolean or, vector or, niente coalescing                                |
 | `x if y else z`                                  | Ternary conditional                                                     |
 | `lest`                                           | Fallback[^1]                                                                |
 

src/ast.ts

@@ -19,7 +19,7 @@ export type UpdateOperator = '++' | '--';
 
 export type BinaryOperator =
   | 'lest'
-  | '??'
+  | 'al'
   | 'or'
   | 'vor'
   | 'and'

src/grammars/sonic-weave.pegjs

@@ -8,6 +8,7 @@
   };
 
   const RESERVED_WORDS = new Set([
+    'al',
     'and',
     'break',
     'by',
@@ -127,6 +128,7 @@ Program
     };
   }
 
+AlToken            = @'al'       !IdentifierPart
 AndToken           = @'and'      !IdentifierPart
 BreakToken         = @'break'    !IdentifierPart
 ByToken            = @'by'       !IdentifierPart
@@ -608,7 +610,7 @@ ConditionalExpression
     return result;
   }
 
-CoalescingOperator = '??' / OrToken / VectorOrToken
+CoalescingOperator = AlToken / OrToken / VectorOrToken
 
 CoalescingExpression
   = head: ConjunctionExpression tail: (__ @CoalescingOperator _ @ConjunctionExpression)* {

src/parser/__tests__/sonic-weave-ast.spec.ts

@@ -301,13 +301,13 @@ describe('SonicWeave Abstract Syntax Tree parser', () => {
   });
 
   it('parses coalescing reassignment', () => {
-    const ast = parseSingle('x ??= 42');
+    const ast = parseSingle('x al= 42');
     expect(ast).toEqual({
       type: 'AssignmentStatement',
       name: {type: 'Identifier', id: 'x'},
       value: {
         type: 'BinaryExpression',
-        operator: '??',
+        operator: 'al',
         left: {type: 'Identifier', id: 'x'},
         right: {type: 'IntegerLiteral', value: 42n},
         preferLeft: false,

src/parser/expression.ts

@@ -1217,7 +1217,7 @@ export class ExpressionVisitor {
             case 'tmpr':
               throw new Error('Tempering needs an interval and a val.');
             case 'lest':
-            case '??':
+            case 'al':
             case 'or':
             case 'and':
             case '==':
@@ -1334,7 +1334,7 @@ export class ExpressionVisitor {
           case 'tmpr':
             throw new Error('Tempering needs an interval and a val.');
           case 'lest':
-          case '??':
+          case 'al':
           case 'or':
           case 'and':
           case 'of':
@@ -1635,7 +1635,7 @@ export class ExpressionVisitor {
       }
     }
     const left = this.visit(node.left);
-    if (operator === '??') {
+    if (operator === 'al') {
       if (left !== undefined) {
         return left;
       }

src/stdlib/prelude.ts

@@ -663,7 +663,7 @@ riff realizeWord(word, sizes, equave = niente) {
     throw "Only a single step size may be omitted.";
   }
   if (numMissing == 1) {
-    equave ??= 2;
+    equave al= 2;
     let total = 1;
     for (const [letter, count] of entries(signature)) {
       if (letter == missingLetter)