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diff --git a/Omni/Bild/Meta.hs b/Omni/Bild/Meta.hs
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+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+-- | Small module for extracting metadata from the comments of modules.
+module Omni.Bild.Meta where
+
+import Alpha
+import qualified Data.Aeson as Aeson
+import qualified Data.Char as Char
+import qualified Data.Set as Set
+import qualified Data.Text as Text
+import qualified Text.Regex.Applicative as Regex
+
+-- | A third-party dependency. This gets mapped to some name in nixpkgs,
+-- prefixed by package set like @haskellPackages@ or
+-- @python3Packages@.
+type Dep = String
+
+-- | This is a system-level requirement, the string gets mapped to a name in
+-- nixpkgs at the top level, like @pkgs.thing@.
+type Sys = String
+
+-- | A run-time dependency. This is some executable that will be placed on
+-- @PATH@. This gets selected from @bild.pkgs@, so it must be exported there.
+type Run = String
+
+-- | An arbitrary compiler argument that may get added to the compilation
+-- command. Should be used sparingly, and not all builds will support this.
+type Arg = String
+
+data Out = Lib String | Bin String | None
+  deriving (Show, Eq)
+
+instance Aeson.ToJSON Out where
+  toJSON =
+    Aeson.String <. Text.pack <. \case
+      Bin a -> a
+      Lib a -> a
+      None -> ""
+
+data Parsed = Parsed
+  { pdep :: Set Dep,
+    parg :: Set Arg,
+    pout :: Out,
+    psys :: Set Sys,
+    prun :: Set Run
+  }
+
+detect :: (Ord a) => Regex.RE Char a -> [Text] -> Set a
+detect m cl =
+  cl
+    /> Text.unpack
+    /> Regex.match m
+    |> catMaybes
+    |> Set.fromList
+
+-- | 'Out' is always singular, so it gets a special function
+detectOut :: Regex.RE Char Out -> [Text] -> Out
+detectOut m cl =
+  cl
+    /> Text.unpack
+    /> Regex.match m
+    |> catMaybes
+    |> head
+    |> fromMaybe None
+
+detectAll :: [Char] -> [Text] -> Parsed
+detectAll m cl = Parsed {..}
+  where
+    pout = detectOut (out m <|> lib m) cl
+    detect_ re = detect (re m) cl
+    pdep = detect_ dep
+    psys = detect_ sys
+    parg = detect_ arg
+    prun = detect_ run
+
+dep :: [Char] -> Regex.RE Char Dep
+dep comment =
+  Regex.string (comment ++ " : dep ")
+    *> Regex.many (Regex.psym (not <. Char.isSpace))
+
+sys :: [Char] -> Regex.RE Char Dep
+sys comment =
+  Regex.string (comment ++ " : sys ")
+    *> Regex.many (Regex.psym (not <. Char.isSpace))
+
+out :: [Char] -> Regex.RE Char Out
+out comment =
+  Regex.string (comment ++ " : out ")
+    *> Regex.many (Regex.psym (/= ' '))
+    /> Bin
+
+lib :: [Char] -> Regex.RE Char Out
+lib comment =
+  Regex.string (comment ++ " : lib ")
+    *> Regex.many (Regex.psym (/= ' '))
+    /> Lib
+
+arg :: [Char] -> Regex.RE Char Arg
+arg comment =
+  Regex.string (comment ++ " : arg ")
+    *> Regex.many Regex.anySym
+
+run :: [Char] -> Regex.RE Char Run
+run comment =
+  Regex.string (comment ++ " : run ")
+    *> Regex.many Regex.anySym