list splatterns!

src/main.rs

@@ -55,7 +55,7 @@ use crate::base::*;
 
 pub fn main() {
     let src = "
-let (x, y, ...z) = (1, 2, 3)
+let [x, y, ...z] = [1, 2, 3, 4]
 z
     ";
     let (tokens, lex_errs) = lexer().parse(src).into_output_errors();

src/vm.rs

@@ -110,16 +110,28 @@ pub fn match_pattern<'src, 'a>(
             Some(ctx)
         }
         (Pattern::List(x), Value::List(y)) => {
-            if x.len() != y.len() {
+            let has_splat = x.iter().any(|patt| {
+                if let (Pattern::Splattern(_), _) = patt {
+                    true
+                } else {
+                    false
+                }
+            });
+            if x.len() > y.len() || (!has_splat && x.len() != y.len()) {
                 return None;
             };
             let to = ctx.len();
             for i in 0..x.len() {
-                if let None = match_pattern(&x[i].0, y.get(i).unwrap(), ctx) {
-                    while ctx.len() > to {
-                        ctx.pop();
+                if let Pattern::Splattern(patt) = &x[i].0 {
+                    let list = Value::List(y.skip(i));
+                    match_pattern(&(*patt).0, &list, ctx);
+                } else {
+                    if let None = match_pattern(&x[i].0, &y.get(i).unwrap(), ctx) {
+                        while ctx.len() > to {
+                            ctx.pop();
+                        }
+                        return None;
                     }
-                    return None;
                 }
             }
             Some(ctx)