feat: ignore underscores in input

this isn't useful for typst usually,
since underscores are subscript and don't appear in expressions much.

however, when using tylc as a standalone calculator,
this is useful eg to seperate sets of three digits.

idea totally stolen from rust literals

src/formatting.rs

@@ -2,7 +2,9 @@ use rug::Float;
 
 use crate::nodes::{self, Error};
 
-pub fn pretty_eval(mut input: String, max_digits: usize) -> Result<String, Error> {
+pub fn pretty_eval(input: &str, max_digits: usize) -> Result<String, Error> {
+    let mut input = input.replace('_', "");
+
     // no need to remove the characters here,
     // as we ignore the them in all other logic already
     let should_add_back_alignment = input.contains('&');
@@ -49,20 +51,20 @@ pub fn pretty_eval(mut input: String, max_digits: usize) -> Result<String, Error
 }
 #[test]
 fn test_character_readdition() {
-    assert_eq!(pretty_eval(" = 11".into(), 10).unwrap(), " = 11");
+    assert_eq!(pretty_eval(" = 11", 10).unwrap(), " = 11");
-    assert_eq!(pretty_eval(" &= 11".into(), 10).unwrap(), " & = 11");
+    assert_eq!(pretty_eval(" &= 11", 10).unwrap(), " & = 11");
-    assert_eq!(pretty_eval(" & 11".into(), 10).unwrap(), " & 11");
+    assert_eq!(pretty_eval(" & 11", 10).unwrap(), " & 11");
-    assert_eq!(pretty_eval(" & 11 \\".into(), 10).unwrap(), " & 11 \\");
+    assert_eq!(pretty_eval(" & 11 \\", 10).unwrap(), " & 11 \\");
 }
 #[test]
 fn test_basic_up_to_999() {
-    assert_eq!(pretty_eval("1".into(), 10).unwrap(), "1");
+    assert_eq!(pretty_eval("1", 10).unwrap(), "1");
-    assert_eq!(pretty_eval("10".into(), 10).unwrap(), "10");
+    assert_eq!(pretty_eval("10", 10).unwrap(), "10");
-    assert_eq!(pretty_eval("100".into(), 10).unwrap(), "100");
+    assert_eq!(pretty_eval("100", 10).unwrap(), "100");
-    assert_eq!(pretty_eval("999".into(), 10).unwrap(), "999");
+    assert_eq!(pretty_eval("999", 10).unwrap(), "999");
-    assert_eq!(pretty_eval("1000".into(), 10).unwrap(), "1 * 10^3");
+    assert_eq!(pretty_eval("1000", 10).unwrap(), "1 * 10^3");
 
-    assert_eq!(pretty_eval("11.111111".into(), 10).unwrap(), "11.111111");
+    assert_eq!(pretty_eval("11.111111", 10).unwrap(), "11.111111");
 }
 
 pub fn get_significant_digits(n: &Float) -> usize {

src/main.rs

@@ -17,7 +17,7 @@ fn main() -> ExitCode {
             buf
         });
 
-    match lib::formatting::pretty_eval(input, 10) {
+    match lib::formatting::pretty_eval(&input, 10) {
         Ok(s) => println!("{s}"),
 
         Err(e) => {