From 77d2826918e9013efaf70bfe7884aaeb46075feb Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Mon, 5 Nov 2018 14:01:14 -0800
Subject: [PATCH] Pattern-match on structured objects

---
 schala-lang/language/src/eval.rs | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/schala-lang/language/src/eval.rs b/schala-lang/language/src/eval.rs
index ec820f6..a10e538 100644
--- a/schala-lang/language/src/eval.rs
+++ b/schala-lang/language/src/eval.rs
@@ -403,6 +403,15 @@ impl<'a> State<'a> {
 
     //TODO need to handle recursive subpatterns
     let all_subpatterns_pass = |state: &mut State, subpatterns: &Vec<Option<Subpattern>>, items: &Vec<Node>| -> EvalResult<bool> {
+
+      if subpatterns.len() == 0 {
+        return Ok(true)
+      }
+
+      if items.len() != subpatterns.len() {
+        return Err(format!("Subpattern length isn't correct items {} subpatterns {}", items.len(), subpatterns.len()));
+      }
+
       for (maybe_subp, cond) in subpatterns.iter().zip(items.iter()) {
         if let Some(subp) = maybe_subp {
           if !state.guard_passes(&subp.guard, &cond)? {
@@ -425,19 +434,20 @@ impl<'a> State<'a> {
         Node::PrimObject { ref tag, ref items, .. } => {
           if alt.tag.map(|t| t == *tag).unwrap_or(true) {
             let mut inner_state = self.new_frame(items, &alt.bound_vars);
-            return inner_state.block(alt.item)
+            if all_subpatterns_pass(&mut inner_state, &alt.subpatterns, items)? {
+              return inner_state.block(alt.item);
+            } else {
+              continue;
+            }
           }
         },
         Node::PrimTuple { ref items } =>  {
-          if items.len() != alt.subpatterns.len() {
-            return Err(format!("Subpattern length isn't correct"));
-          }
-
           let mut inner_state = self.new_frame(items, &alt.bound_vars);
-          if !all_subpatterns_pass(&mut inner_state, &alt.subpatterns, items)? {
+          if all_subpatterns_pass(&mut inner_state, &alt.subpatterns, items)? {
+            return inner_state.block(alt.item);
+          } else {
             continue;
           }
-          return inner_state.block(alt.item)
         },
         Node::Expr(ref _e) => {
           if let None = alt.tag {