Check role of single-token left argument when determining valence

2 files changed, 2 insertions, 1 deletions

diff --git a/dc.bqn b/dc.bqn
index ebe71811..3b8958e0 100755
--- a/dc.bqn
+++ b/dc.bqn
@@ -145,7 +145,7 @@ DParse ← {nv‿r𝕊𝕩:
   tf←tr∧2(|<≤)ps(⊢-⌈`∘×)+`¬ro∨op
   opa←op>1↓0∾˜ps∨a⋄os←⌽↕∘≠⊸(⊣-⌈`∘×)⌽¬ro∨¯1⊸⌽⊸∨op
   oa←⌽/opa⋄fa←/(ro∧1⌽opa)<((tr∨op)<f∨¯1⌽opa)∨tf∧a<○(⌈`(1+↕∘≠)⊸×)ps
-  dy←fa⊏1↓0∾˜(tr>tf∨ps)∨v∨lc∨f<𝕩=1⊑bB
+  dy←fa⊏1↓0∾˜(tr>tf∨ps)∨(v∧r=0)∨lc∨f<𝕩=1⊑bB
   n←𝕩≥vi+nv⋄id←/v-n⋄cn←/n∨𝕩≤¯1⊑bC⋄u←⍷ob←cn⊏𝕩
   lo←(o/𝕩)=4⊑bB⋄l←/lc⋄ll←1+lo/1(↓--⊸↓)(o∾1)/+`s∾0
   dr←/s>(+`o)⊏0∾lo
diff --git a/test/bcases.bqn b/test/bcases.bqn
index f3a6db0a..ee134c5c 100644
--- a/test/bcases.bqn
+++ b/test/bcases.bqn
@@ -17,3 +17,4 @@
 1    % -´⟨2×3⋄5⟩
 2    % (4-⟨0,1⟩×2)⊑˜1
 16   % 3(2×+⍟(1+1))2
+-1   % f←0⊑⟨×,-⟩⋄F 2 F -4