make defaults work, like magic

src/compiler/tests/compiler.test.ts

@@ -282,3 +282,19 @@ describe('dot get', () => {
     expect(`a = 1; arr = array 'a' 'b' 'c'; arr.(1 + a)`).toEvaluateTo('c', { array })
   })
 })
+
+describe('default params', () => {
+  test('parses function with single default parameter', () => {
+    expect('add1 = do x=1: x + 1 end; add1').toEvaluateTo(2)
+    expect('add1 = do x=1: x + 1 end; add1 5').toEvaluateTo(6)
+  })
+
+  test('parses function with multiple default parameters', () => {
+    expect(`weird = do x='something' y=true: [x y] end; weird`).toEvaluateTo(['something', true])
+  })
+
+  test('parses function with mixed parameters', () => {
+    expect('multiply = do x y=5: x * y end; multiply 5').toEvaluateTo(25)
+    expect('multiply = do x y=5: x * y end; multiply 5 2').toEvaluateTo(10)
+  })
+})

src/compiler/utils.ts

@@ -99,9 +99,9 @@ export const getFunctionDefParts = (node: SyntaxNode, input: string) => {
   }
 
   const paramNames = getAllChildren(paramsNode).map((param) => {
-    if (param.type.id !== terms.Identifier) {
+    if (param.type.id !== terms.Identifier && param.type.id !== terms.NamedParam) {
       throw new CompilerError(
-        `FunctionDef params must be Identifier, got ${param.type.name}`,
+        `FunctionDef params must be Identifier or NamedParam, got ${param.type.name}`,
         param.from,
         param.to
       )