patterns: fix a regression in field injection

src/syndicate/patterns.nim

@@ -170,11 +170,10 @@ proc fieldCount(T: typedesc): int =
   for _, _ in fieldPairs(default T):
     inc result
 
-proc match(bindings: sink openArray[(int, Pattern)]; i: int; pat: var Pattern): bool =
+proc lookup[T](bindings: openArray[(int, Pattern)]; i: int; _: T): Pattern =
   for (j, b) in bindings:
-    if i == j:
-      pat = b
-      return true
+    if i == j: return b
+  return dropType(T)
 
 proc grab*(typ: static typedesc; bindings: sink openArray[(int, Pattern)]): Pattern =
   ## Construct a `Pattern` from type `typ` that selectively captures fields.
@@ -185,8 +184,7 @@ proc grab*(typ: static typedesc; bindings: sink openArray[(int, Pattern)]): Patt
     rec.fields.setLen(fieldCount typ)
     var i: int
     for _, f in fieldPairs(default typ):
-      if not match(bindings, i, rec.fields[i]):
-        rec.fields[i] = dropType(typeof f)
+      rec.fields[i] = lookup(bindings, i, f)
       inc i
     result = rec.toPattern
   elif typ is tuple:
@@ -194,8 +192,7 @@ proc grab*(typ: static typedesc; bindings: sink openArray[(int, Pattern)]): Patt
     arr.items.setLen(fieldCount typ)
     var i: int
     for _, f in fieldPairs(default typ):
-      if not match(bindings, i, arr.items[i]):
-        arr.items[i] = dropType(typeof f)
+      arr.items[i] = lookup(bindings, i, f)
       inc i
     result = arr.toPattern
   else:

syndicate.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version = "20230816"
+version = "20230822"
 author        = "Emery Hemingway"
 description   = "Syndicated actors for conversational concurrency"
 license       = "Unlicense"