Common.throw() Function

.changeset/smooth-fireants-flash.md

@@ -0,0 +1,5 @@
+---
+"@quri/squiggle-lang": patch
+---
+
+Added Common.throw

packages/squiggle-lang/src/errors/messages.ts

@@ -187,3 +187,14 @@ export class REAmbiguous extends ErrorMessage {
     return `Ambiguous Error: ${this.message}`;
   }
 }
+
+// Used for user-created throw() function calls
+export class REThrow extends ErrorMessage {
+  constructor(public msg: string) {
+    super(msg);
+  }
+
+  toString() {
+    return `${this.message}`;
+  }
+}

packages/squiggle-lang/src/fr/builtin.ts → packages/squiggle-lang/src/fr/common.ts

@@ -1,3 +1,4 @@
+import { REThrow } from "../errors/messages.js";
 import { makeDefinition } from "../library/registry/fnDefinition.js";
 import {
   frAny,
@@ -55,4 +56,22 @@ export const library = [
       ),
     ],
   }),
+  maker.make({
+    name: "throw",
+    description:
+      "Throws a fatal error. There is no way in the language to catch this error.",
+    definitions: [
+      makeDefinition(
+        [frOptional(frNamed("message", frString))],
+        frAny(),
+        ([value]) => {
+          if (value) {
+            throw new REThrow(value);
+          } else {
+            throw new REThrow("Common.throw() was called");
+          }
+        }
+      ),
+    ],
+  }),
 ];

packages/squiggle-lang/src/library/registry/index.ts

@@ -1,5 +1,5 @@
 import { library as booleanLibrary } from "../../fr/boolean.js";
-import { library as builtinLibrary } from "../../fr/builtin.js";
+import { library as commonLibrary } from "../../fr/common.js";
 import { library as calculatorLibrary } from "../../fr/calculator.js";
 import { library as dangerLibrary } from "../../fr/danger.js";
 import { library as dateLibrary } from "../../fr/date.js";
@@ -54,7 +54,7 @@ const fnList: FRFunction[] = [
   ...unitsLibrary,
   ...calculatorLibrary,
   ...inputLibrary,
-  ...builtinLibrary, // should go last, because has some catch-all functions
+  ...commonLibrary, // should go last, because has some catch-all functions
 ];
 
 export const registry = Registry.make(fnList);