diff --git a/tools/lsp/squirrel/app/Main.hs b/tools/lsp/squirrel/app/Main.hs
index 19f6b7c64..4a598852d 100644
--- a/tools/lsp/squirrel/app/Main.hs
+++ b/tools/lsp/squirrel/app/Main.hs
@@ -30,6 +30,7 @@ import           Range
 import           AST hiding (def)
 import           HasErrors
 import           Pretty
+import           Error
 
 main :: IO ()
 main = do
diff --git a/tools/lsp/squirrel/src/AST/Scope.hs b/tools/lsp/squirrel/src/AST/Scope.hs
index c7ab2708e..fdfc68bfa 100644
--- a/tools/lsp/squirrel/src/AST/Scope.hs
+++ b/tools/lsp/squirrel/src/AST/Scope.hs
@@ -1,12 +1,25 @@
 
-{-
-  The AST and auxillary types along with their pretty-printers.
-
-  TODO: Untangle pretty-printing mess into combinators.
-  TODO: Store offending text verbatim in Wrong*.
+{- | /The/ scope resolution system.
 -}
 
-module AST.Scope where
+module AST.Scope
+  ( -- * Monad
+    ScopeM
+  , evalScopeM
+
+    -- * Scope
+  , Env(..)
+  , ScopedDecl(..)
+  , Kind(..)
+
+    -- * Methods
+  , enter
+  , leave
+  , define
+  , defType
+  , def
+  )
+  where
 
 import Control.Lens hiding (Const, List)
 import Control.Monad.State
diff --git a/tools/lsp/squirrel/src/AST/Types.hs b/tools/lsp/squirrel/src/AST/Types.hs
index b8b7e06a8..3f4b4437e 100644
--- a/tools/lsp/squirrel/src/AST/Types.hs
+++ b/tools/lsp/squirrel/src/AST/Types.hs
@@ -1,6 +1,7 @@
 
-{- |
-  The AST and auxillary types along with their pretty-printers.
+{- | The AST and auxillary types along with their pretty-printers.
+
+     The comments for fields in types are the type before it was made untyped.
 -}
 
 module AST.Types where
@@ -32,7 +33,7 @@ type Pascal = Tree
   ]
 
 data Contract it
-  = Contract      [it]
+  = Contract      [it] -- ^ Declaration
   deriving (Show) via PP (Contract it)
   deriving stock (Functor, Foldable, Traversable)
 
@@ -84,7 +85,7 @@ data TField it
   deriving (Show) via PP (TField it)
   deriving stock (Functor, Foldable, Traversable)
 
--- | TODO: break onto smaller types? Literals -> Constannt; mapOps; mmove Annots to Decls.
+-- | TODO: break onto smaller types? Literals -> Constant; mapOps; mmove Annots to Decls.
 data Expr it
   = Let       [it] it -- [Declaration] (Expr)
   | Apply     it [it] -- (Expr) [Expr]
diff --git a/tools/lsp/squirrel/src/ParseTree.hs b/tools/lsp/squirrel/src/ParseTree.hs
index 6c06fc2f8..ff31bbd11 100644
--- a/tools/lsp/squirrel/src/ParseTree.hs
+++ b/tools/lsp/squirrel/src/ParseTree.hs
@@ -1,22 +1,30 @@
 
 {-# language StrictData #-}
 
+{- | The input tree from TreeSitter. Doesn't have any pointers to any data
+     from actual tree the TS produced and therefore has no usage limitations.
+
+     All datatypes here are strict.
+-}
+
 module ParseTree
-  ( ParseTree(..)
+  ( -- * Tree/Forest
+    ParseTree(..)
   , ParseForest(..)
+
+    -- * Invoke the TreeSitter and get the tree it outputs
   , toParseTree
-  , cutOut
   )
   where
 
+import Data.ByteString (ByteString)
 import Data.IORef
+import qualified Data.ByteString as BS
 import qualified Data.Text as Text
 import Data.Text (Text)
 import Data.Traversable (for)
 import Data.Text.Encoding
 import Data.Text.Foreign (withCStringLen)
-import qualified Data.ByteString as BS
-import Data.ByteString (ByteString)
 
 import           TreeSitter.Parser
 import           TreeSitter.Tree
@@ -78,14 +86,6 @@ instance Pretty ParseForest where
         then nest 2 $ pp tree
         else hang (text (Text.unpack field) <> ": ") 2 (pp tree)
 
--- | Extract textual representation of given range.
-cutOut :: Range -> ByteString -> Text
-cutOut (Range (_, _, s) (_, _, f)) bs =
-  decodeUtf8
-    $ BS.take (f - s)
-    $ BS.drop  s
-      bs
-
 -- | Feed file contents into PascaLIGO grammar recogniser.
 toParseTree :: FilePath -> IO ParseForest
 toParseTree fin = do
diff --git a/tools/lsp/squirrel/src/Parser.hs b/tools/lsp/squirrel/src/Parser.hs
index e1b8368d7..263371344 100644
--- a/tools/lsp/squirrel/src/Parser.hs
+++ b/tools/lsp/squirrel/src/Parser.hs
@@ -1,6 +1,6 @@
 
 {- |
-  The thing that can untangle the mess that tree-sitter produced.
+  The thing that can untangle the mess that TreeSitter produces.
 
   In presence of serious errors, it /will/ be a mess, anyway.
 
@@ -33,24 +33,31 @@
 -}
 
 module Parser
-  ( Parser
+  ( -- * Parser type
+    Parser
   , runParser
   , debugParser
+
+    -- * Combinators
   , subtree
   , anything
   , token
-  , ASTInfo(..)
+  , stubbed
   , getInfo
   , inside
+
+    -- * Replacement for `Alternative`, because reasons
   , many
   , some
   , (<|>)
   , optional
   , select
+
+    -- * Debug
   , dump
-  , stubbed
-  , Stubbed (..)
-  , Error (..)
+
+    -- * Comments and ranges
+  , ASTInfo(..)
   ) where
 
 import Control.Lens hiding (inside)
diff --git a/tools/lsp/squirrel/src/Pretty.hs b/tools/lsp/squirrel/src/Pretty.hs
index 7a8f02fcb..2c5330853 100644
--- a/tools/lsp/squirrel/src/Pretty.hs
+++ b/tools/lsp/squirrel/src/Pretty.hs
@@ -1,12 +1,19 @@
 {-
-  Pretty printer, based on GHC one.
+  Pretty printer, a small extension of GHC `pretty` package.
 -}
 
 module Pretty
-  ( ppToText
+  ( -- * Output `Text`
+    ppToText
+
+    -- * `Show` instance generator
   , PP(..)
+
+    -- * Interfaces
   , Pretty(..)
   , Pretty1(..)
+
+    -- * Helpers
   , tuple
   , list
   , indent
@@ -16,6 +23,8 @@ module Pretty
   , sepByDot
   , mb
   , sparseBlock
+
+    -- * Full might of pretty printing
   , module Text.PrettyPrint
   )
   where
diff --git a/tools/lsp/squirrel/src/Range.hs b/tools/lsp/squirrel/src/Range.hs
index f6f5890aa..eed96db17 100644
--- a/tools/lsp/squirrel/src/Range.hs
+++ b/tools/lsp/squirrel/src/Range.hs
@@ -3,11 +3,17 @@ module Range
   ( Range(..)
   , HasRange(..)
   , diffRange
+  , cutOut
   )
   where
 
 import Control.Lens
 
+import qualified Data.ByteString as BS
+import Data.ByteString (ByteString)
+import Data.Text (Text)
+import Data.Text.Encoding
+
 import Pretty
 
 -- | A continious location in text.
@@ -28,4 +34,13 @@ instance Pretty Range where
 
 -- | Ability to get range out of something.
 class HasRange a where
-  getRange :: a -> Range
\ No newline at end of file
+  getRange :: a -> Range
+
+-- | Extract textual representation of given range.
+cutOut :: Range -> ByteString -> Text
+cutOut (Range (_, _, s) (_, _, f)) bs =
+  decodeUtf8
+    $ BS.take (f - s)
+    $ BS.drop  s
+      bs
+
diff --git a/tools/lsp/squirrel/src/Tree.hs b/tools/lsp/squirrel/src/Tree.hs
index 470dc75d4..63b1af450 100644
--- a/tools/lsp/squirrel/src/Tree.hs
+++ b/tools/lsp/squirrel/src/Tree.hs
@@ -1,4 +1,14 @@
 
+{- | The carrier type for AST.
+
+     "Untypedness" of the tree is a payoff to ablity to stop and navigate
+     anywhere, not just inside the expression context.
+
+     Is a `Functor` and `Foldable` over its @info@ parameter.
+     Is not `Traversable`, because this will definitely not preserve scope.
+     Use `updateTree` instead of `traverse`/`for`.
+-}
+
 module Tree
   ( Tree
   , spineTo
@@ -10,6 +20,7 @@ module Tree
 
 import Data.Fix
 import Data.Functor.Compose
+import Data.Foldable
 
 import Union
 import Update
@@ -37,6 +48,12 @@ instance (Functor (Union layers)) => Functor (Tree layers) where
       go (Compose (Right (Compose (a, rest)))) =
         Compose $ Right $ Compose (f a, rest)
 
+instance (Functor (Union layers), Foldable (Union layers)) => Foldable (Tree layers) where
+  foldMap f (Tree fixpoint) = cata go fixpoint
+    where
+      go (Compose (Left err))                  = mempty
+      go (Compose (Right (Compose (a, rest)))) = f a <> fold rest
+
 instance
     ( Functor (Union layers)
     , HasComments info
@@ -71,14 +88,13 @@ spineTo
 spineTo info = reverse . go . unTree
   where
     go tree@(Fix (Compose (Right (Compose (info', fres))))) =
-      -- traceShow (info <? info', info, info') $
       if   info <? info'
       then Tree tree : foldMap go fres
       else []
 
     go _ = []
 
--- | Update the tree over some monad that exports its methods.
+-- | Traverse the tree over some monad that exports its methods.
 --
 --   For each tree piece, will call `before` and `after` callbacks.
 --
@@ -86,8 +102,7 @@ updateTree
   :: ( UpdateOver m (Union fs) (Tree fs a)
      , Traversable  (Union fs)
      )
-  => (a -> m b)
-  -> Tree fs a -> m (Tree fs b)
+  => (a -> m b) -> Tree fs a -> m (Tree fs b)
 updateTree act = fmap Tree . go . unTree
   where
     go (Fix (Compose (Right (Compose (a, union))))) = do
diff --git a/tools/lsp/squirrel/src/Union.hs b/tools/lsp/squirrel/src/Union.hs
index 9d3f1014b..b89d8722e 100644
--- a/tools/lsp/squirrel/src/Union.hs
+++ b/tools/lsp/squirrel/src/Union.hs
@@ -1,7 +1,17 @@
 
+{- | The union of functors and utilities.
+
+-}
+
 module Union
-  ( Union(..), eliminate
-  , Member, proj, inj
+  ( -- * Union type
+    Union(..)
+  , eliminate
+
+    -- * Interface
+  , Member
+  , proj
+  , inj
   )
   where
 
diff --git a/tools/lsp/squirrel/src/Update.hs b/tools/lsp/squirrel/src/Update.hs
index 61eace2bf..b56145aaf 100644
--- a/tools/lsp/squirrel/src/Update.hs
+++ b/tools/lsp/squirrel/src/Update.hs
@@ -1,7 +1,13 @@
 
+{- | Utils for updating the @Tree@ type.
+-}
+
 module Update
-  ( HasMethods(..)
+  ( -- * Interfaces
+    HasMethods(..)
   , UpdateOver(..)
+
+    -- * Default implementation
   , skip
   )
   where