add as patterns

src/main.rs

@@ -53,7 +53,28 @@ use crate::base::*;
 
 pub fn main() {
     let src = "
+fn fancy_add {
+    () -> 0
+    (n as :number) -> n
+    (x as :number, y as :number) -> add (x, y)
+}
 
+fn fancy_sub {
+    () -> 0
+    (n as :number) -> n
+    (x as :number, y as :number) -> sub (x, y)
+}
+
+fn fib {
+   (1) -> 1
+   (2) -> 1
+   (n) -> fancy_add(
+       fib (fancy_sub (n, 1))
+       fib (fancy_sub (n, 2))
+   ) 
+}
+
+fib (30)
     ";
     let (tokens, lex_errs) = lexer().parse(src).into_output_errors();
     if lex_errs.len() > 0 {

src/vm.rs

@@ -67,9 +67,15 @@ pub fn match_pattern<'src, 'a>(
             ctx.push((w, val.clone()));
             Some(ctx)
         }
-        (Pattern::As(word, type_kw), value) => {
+        (Pattern::As(word, type_str), value) => {
             let ludus_type = value.ludus_type();
-            None
+            let type_kw = Value::Keyword(type_str);
+            if type_kw == ludus_type {
+                ctx.push((word, value.clone()));
+                Some(ctx)
+            } else {
+                None
+            }
         }
         // todo: add splats to these match clauses
         (Pattern::Tuple(x), Value::Tuple(y)) => {