From 92bd804e1249774b33f54cc9b8504ac9e72ca651 Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Sun, 28 Nov 2021 19:31:51 -0500
Subject: =?UTF-8?q?Allow=20=C2=B7=20as=20placeholder=20in=20assignment=20a?=
 =?UTF-8?q?nd=20headers?=
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---
 src/c.bqn | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/c.bqn b/src/c.bqn
index a4e6d011..a3cb8468 100644
--- a/src/c.bqn
+++ b/src/c.bqn
@@ -147,7 +147,6 @@ Parse ← {r‿vn‿i‿e‿def←𝕨⋄nv←≠vn
   cp←𝕩=1+⊑bB                                # Closed paren
   nr←(IT¬cp)⊏(𝕩=2+⊑bI)+2×𝕩=⊑bO              # Nothingness role: 1 for 𝕨, 2 for ·
   nx←0 ⋄ nei←↕≠nr ⋄ _nerr←{𝕗 _err_ nei 2=nx⌈↩𝕩}
-  "Can't strand Nothing (·)"_nerr nr׬ns
   g⊏˜↩⍋g⊏sdl←sl∨dl                          # Avoid reordering strands and dots in rev
   rp←≠⊸»⌾(g⊸⊏)↕≠r                           # Position of previous, for roles
   # Permutation to reverse each expression: *more* complicated than it looks
@@ -242,7 +241,6 @@ Parse ← {r‿vn‿i‿e‿def←𝕨⋄nv←≠vn
   "Missing operand"_nerr op×2(«⌈m2×»)no⌈2×m2≥ro∨r∊↕2
   s←𝕩=sep⋄fo←𝕩∊⟨2+⊑bB,1+⊑bH⟩                # Separators, function open { or ;
   ls←s∧fo<○IT lo←𝕩=4+⊑bB                    # List Separators: after ⟨lo, not {fo
-  "Can't use Nothing (·) in lists"_nerr ne×»lo∨ls
   "Double subjects (missing ‿?)"_err_(G) ∧⟜«ro»⊸∨⊸<r=0
   mm←𝕩=2+⊑bG⋄ma←tr<mm∧«ir≥1⋄mm∧↩1»ps        # Modified assignment; monadic modified
   "No right-hand side in non-modified assignment"_err_(G) ma<mm
@@ -252,6 +250,8 @@ Parse ← {r‿vn‿i‿e‿def←𝕨⋄nv←≠vn
   ak←af+(0≤ar)+(ai⊏ma)+(⊑bG)-˜ai⊏𝕩          # Class of assignment: 1⇐ 2⇐? 3←? 4↩? 5+↩?
   at∾↩hj⋄ac←«⊸-(ak∾6¨hj)⌾(at⊸⊏)0¨𝕩          # Header assignment is 6 temporarily
   aa←×gac←g⊏ac↩»+`(1⊸»⊸∨0=+`)⊸×gi⊏ac        # Broadcast ac to the entire target
+  api←/ap←aa∧2=no                           # Assignment placeholder
+  "Can't use Nothing (·) in lists"_nerr (¬ap)×no×(gr⊏¬ns)∨»lo∨ls
   ac-↩3×ah←6=ac                             # Assignment is header; 6→3
   nx⌈↩aa×1=no                               # Prevent assignment to 𝕨 if it's ·
   nf←H ac<xv=vi-˜⊑bG                        # Namespace bodies
@@ -264,7 +264,7 @@ Parse ← {r‿vn‿i‿e‿def←𝕨⋄nv←≠vn
   aid←(¯6⊸≤∧<⟜nv)𝕩-vi                       # Assignable identifer
   hq←/hp←(g⊏ah)∧𝕩≥nv+vi                     # Header constant
   atc←(hg<ps<«aa∧r≥0)<aid∨hp∨(ps>«𝕩=⊑bL)∨𝕩(=⟜(3+⊑)<M)bB
-  "Assignment target must be a name or list of targets"_err_(G) (a∨atc)<aa
+  "Assignment target must be a name or list of targets"_err_(G) (a∨atc∨ap)<aa
   "Can't nest assignments (write aliases with ⇐)"_err_(ai⊏G) ((5≠ai⊏gac)∧ak=2)<ai⊏aa
   "Can't use result of function/modifier assignment without parentheses"_err_(G) hg<(0<er)∧(0≤r)∧»⊸>aa
   af>↩alm←ai⊏aa⋄al←alm/ai                   # aliases al
@@ -318,8 +318,8 @@ Parse ← {r‿vn‿i‿e‿def←𝕨⋄nv←≠vn
 
   # Object code generation: numbers oc ordered by source location (after rev) oi
   ao←48+(0⌈(1+⊑bG)-˜ai⊏𝕩+ma+mm)∾-hd         # Assignment opcode
-  or←⍋oi←idor∾g⊏˜∾⟨cn,cn,bk,bk,hq,2/l,at,dr,qp,al+1,al+1,oa+1⌈oa⊏os,fl,rt⟩
-  oc←or⊏∾idoc∾⟨0¨cn,ob,1¨bk,1+↕≠bk,43¨hq,⥊⍉(11+l⊏aa)≍ll,ao,6¨dr,42¨qp,66¨al,vi-˜(al-1)⊏𝕩
+  or←⍋oi←idor∾g⊏˜∾⟨cn,cn,bk,bk,hq,2/l,api,at,dr,qp,al+1,al+1,oa+1⌈oa⊏os,fl,rt⟩
+  oc←or⊏∾idoc∾⟨0¨cn,ob,1¨bk,1+↕≠bk,43¨hq,⥊⍉(11+l⊏aa)≍ll,44¨api,ao,6¨dr,42¨qp,66¨al,vi-˜(al-1)⊏𝕩
                24+oa⊏r,16+(fn/dy+2×fm⌈1=ny)+4×0<fa⊏er,¯1↓rc←7+nf⟩
   # Instruction source positions
   MI←-⊸↓˜⟜≠∾g⊏˜⊢⋄oj←(rt-∘≠⊸⌽oi⌊1-˜≠i)Mi∾⟨1-˜at,oa,fa⟩
-- 
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