Modularize UI, make it a bit more Lisp independent

src/ui/languages/lisp/format.ts

@@ -0,0 +1,45 @@
+import type { FoundSyntax, ParseError } from '../../../languages/lisp';
+import { spanLabel } from '../../format';
+
+export function errorTitle(error: ParseError): string {
+  switch (error.tag) {
+    case "expected-expression":
+      return "Expected expression";
+    case "expected-close-delimiter":
+      return "Expected closing delimiter";
+    case "unexpected-close-delimiter":
+      return "Unexpected closing delimiter";
+    case "expected-list-separator":
+      return "Expected list separator";
+    case "unexpected-code-point":
+      return "Unexpected code point";
+    case "invalid-number":
+      return "Invalid number";
+  }
+}
+
+export function errorDetail(error: ParseError): string {
+  switch (error.tag) {
+    case "expected-expression":
+      return `found ${foundLabel(error.found)}`;
+    case "expected-close-delimiter":
+      return `expected ${error.expected}, opened at ${spanLabel(error.open)}, found ${foundLabel(error.found)}`;
+    case "unexpected-close-delimiter":
+      return `${error.delimiter} ${spanLabel(error.span)}`;
+    case "expected-list-separator":
+      return `found ${foundLabel(error.found)}`;
+    case "unexpected-code-point":
+      return `found ${foundLabel(error.found)}`;
+    case "invalid-number":
+      return `${error.reason}: ${error.text}`;
+  }
+}
+
+function foundLabel(found: FoundSyntax): string {
+  switch (found.tag) {
+    case "eof":
+      return `EOF ${spanLabel(found.span)}`;
+    case "code-point":
+      return `${String.fromCodePoint(found.value)} ${spanLabel(found.span)}`;
+  }
+}