nice errors

src/lib.rs

@@ -1,15 +1,25 @@
 mod alloc;
+mod errors;
 mod lex;
 mod parse;
 
 pub fn run_program(program: &str) {
     let lexer = lex::Lexer::lex(program);
-    let tokens: Result<Vec<_>, _> = lexer.collect();
-    println!(
-        "{:#?}",
-        tokens.map(|tokens| tokens
+    let (success, errors) = lexer.partition::<Vec<_>, _>(|result| result.is_ok());
+
+    if errors.is_empty() {
+        println!(
+            "{:#?}",
+            success
+                .into_iter()
+                .map(Result::unwrap)
+                .map(|token| token.kind)
+                .collect::<Vec<_>>()
+        );
+    } else {
+        errors
             .into_iter()
-            .map(|token| token.kind)
-            .collect::<Vec<_>>())
-    );
+            .map(Result::unwrap_err)
+            .for_each(|err| crate::errors::display_error(program, err));
+    }
 }