rearranging dealloc arguments

cps.nim

@@ -181,11 +181,12 @@ proc alloc*[T: Continuation](root: typedesc[T]; c: typedesc): c {.used, inline.}
   ## allocation.
   new c
 
-template dealloc*[T: Continuation](t: typedesc[T];
-                                   c: sink Continuation) {.used.} =
-  ## Reimplement this symbol to customize continuation
-  ## deallocation.
-  discard
+proc dealloc*[T: Continuation](c: sink T; E: typedesc[T]): E {.used, inline.} =
+  ## Reimplement this symbol to customize continuation deallocation;
+  ## `c` is the continuation to be deallocated, while `E` is the type of
+  ## its environment.  This procedure should generally return `nil`, as
+  ## its result may be assigned to another continuation reference.
+  nil
 
 {.push experimental: "callOperator".}
 template `()`(c: Continuation): untyped {.used.} =

cps/hooks.nim

@@ -133,9 +133,7 @@ proc hook*(hook: static[Hook]; a, b: NormNode): NormNode =
       NormNode newNilLit()
   of Dealloc:
     # dealloc(env_234234, continuation)
-    newStmtList [
-      Dealloc.entrace(a, b, newCall(hook.sym, a, b)),
-      NormNode newNilLit()
-    ]
+    Dealloc.entrace a, b:
+      newCall(hook.sym, a, b)
   else:
     b.errorAst "the " & $hook & " hook doesn't take two arguments"

cps/returns.nim

@@ -58,7 +58,7 @@ proc terminator*(c: Name; T: NormNode): NormNode =
   ## or simply set the fn to nil and return the continuation.
   let coop = NimNode hook(Coop, asName"result")
   let pass = NimNode hook(Pass, c, c.dot "mom")
-  let dealloc = NimNode hook(Dealloc, T, c)
+  let dealloc = NimNode hook(Dealloc, c, T)
   let c = NimNode c
   NormNode:
     quote:

tests/thooks.nim

@@ -119,7 +119,7 @@ suite "hooks":
   block:
     ## custom continuation deallocators can nil the continuation
     shouldRun 4:
-      proc dealloc[T: Cont](t: typedesc; c: sink T) =
+      proc dealloc[T: Cont](c: sink T; E: typedesc[T]): E =
         ran()
         c = nil
 
@@ -140,7 +140,7 @@ suite "hooks":
   block:
     ## custom continuation deallocators work with whelp
     shouldRun 4:
-      proc dealloc[T: Cont](t: typedesc; c: sink T) =
+      proc dealloc[T: Cont](c: sink T; E: typedesc[T]): E =
         ran()
         c = nil