footnotes for events/01

1 files changed, 16 insertions, 4 deletions

diff --git a/provider/posts/events/01.lhs b/provider/posts/events/01.lhs
index fd1bd03..01e769e 100644
--- a/provider/posts/events/01.lhs
+++ b/provider/posts/events/01.lhs
@@ -73,7 +73,7 @@ We are going to want to parse a specification of some kind into a form we can ru
 Below we see one such form.
 
 `ListT`{.haskell} allows for nondeterministic computation – it allows us to split
-our wordline and continue depth-first much like `[]`{.haskell}.
+our wordline[^worldlineSplits] and continue depth-first much like `[]`{.haskell}.
 
 Within every wordline we modify a distinct snapshot of `ObjCtx`{.haskell} we took
 while branching.
@@ -83,7 +83,7 @@ We also share one `EvalCtx`{.haskell} across all worldlines.
 > type Eval m a = StateT ObjCtx (ListT (StateT EvalCtx m)) a
 
 `ListT`{.haskell} does not ship with extensive support for the
-[transformers package][transformers]:
+[transformers package][transformers][^pipes]:
 
 > instance MonadState s m => MonadState s (ListT m) where
 >   get = lift get
@@ -92,7 +92,7 @@ We also share one `EvalCtx`{.haskell} across all worldlines.
 The context shared among all worldlines mainly contains all objects that
 eventually get computed – haskells lazyness ensures that we terminate as
 long as we don´t have objects depend on themselves in a sufficiently
-degenerate way.
+degenerate way[^degenerate].
 
 > data EvalCtx = EvalCtx
 >                { _ctxEvents :: [Object]
@@ -105,7 +105,7 @@ degenerate way.
 >         }
 
 Every wordline constructs exactly one object while having access to a set
-of declarations that can occur anywhere on the wordline.
+of declarations that can occur anywhere on the wordline[^ctxVars].
 
 > data ObjCtx = ObjCtx
 >               { _objOccurs :: Bool
@@ -135,8 +135,20 @@ layers to depend on one another:
 >   where
 >     x' = evalStateT (ListT.toList (objCtx <$> execStateT x def)) . flip (set ctxEvents) def . catMaybes
 
+[^ctxVars]: In the base version of this file we carry declarations we may refer to when
+    creating objects (`_objVars`{.haskell}) within `EvalCtx`{.haskell} instead of `ObjCtx`{.haskell}.
+    Why is that a bad idea?
+
+[^worldlineSplits]: What does such a branching point look like in do notation?
+
+[^pipes]: It has been pointed out to me that `ListT`{.haskell} from [pipes][] does.
+
+[^degenerate]: Constructing an example that doesn´t terminate is trivial. Try constructing one that does while
+    still being self-referential!
+
 [Google Calendar]: <https://calendar.google.com>
 [Remind]: <https://www.roaringpenguin.com/products/remind>
 [JSON]: <https://en.wikipedia.org/wiki/JSON>
 [monad transformers]: <https://en.wikibooks.org/wiki/Haskell/Monad_transformers>
 [transformers]: <https://hackage.haskell.org/package/transformers>
+[pipes]: <https://hackage.haskell.org/package/pipes>