From c374635a36d71e8cfff6e1c19b62e5d0e14ea371 Mon Sep 17 00:00:00 2001
From: Estevan Castilho <tevo@riajuu.net>
Date: Wed, 15 Jul 2026 01:52:38 +0000
Subject: Storage layer scaffolding, LMDB backend

---
 lib/concepts/Configuration.ml | 71 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+), 1 deletion(-)

(limited to 'lib/concepts/Configuration.ml')

diff --git a/lib/concepts/Configuration.ml b/lib/concepts/Configuration.ml
index 06434c2..5ca95d5 100644
--- a/lib/concepts/Configuration.ml
+++ b/lib/concepts/Configuration.ml
@@ -1 +1,70 @@
-type configuration = unit
+open Sexplib.Sexp
+
+type term = Sexplib.Sexp.t
+
+module Error = struct
+  open Condition
+
+  let missing_key key =
+    condition "missing-key" "An expected key was not found" ("key" |=| Value.String key)
+
+  let mismatched_tag expected actual =
+    condition "mismatched-tag" "A tag did not match what was expected"
+      ("expected" |=| Value.String expected & "actual" |=| Value.String actual)
+
+  let syntax_error form =
+    condition "syntax-error" "Syntax error"
+      ("form" |=| Value.String (Sexplib.Sexp.to_string_hum form))
+
+  let tagless_form form =
+    condition "tagless-form" "Cannot take tag of an atom or an empty list"
+      ~parent:(syntax_error form) empty
+
+  let bodyless_form form =
+    condition "bodyless-form" "Cannot take body of an atom or an empty list"
+      ~parent:(syntax_error form) empty
+
+  let malformed_pair form =
+    condition "malformed-pair" "Expected a pair of key and value" ~parent:(syntax_error form) empty
+
+  let expected_atom form =
+    condition "expected-atom" "Expected atom but got list structure" ~parent:(syntax_error form)
+      empty
+
+  let not_a_number form =
+    condition "not-a-number" "Could not parse value as number" ~parent:(syntax_error form) empty
+end
+
+let term_of_sexp t = t
+let tag_of = function List (Atom tag :: _) -> Ok tag | form -> Error (Error.tagless_form form)
+let body_of = function List (_ :: body) -> Ok body | form -> Error (Error.bodyless_form form)
+
+type dictionary = (string, term) BatMap.t
+
+let value_for k ?default d =
+  let default = Option.to_result ~none:(Error.missing_key k) default in
+  BatMap.find_opt k d |> Option.map (fun x -> Ok x) |> Option.value ~default
+
+let as_dictionary t tag : (dictionary, Condition.condition) result =
+  let open Utilities.Result in
+  let strip_tag (tag : string) (t : term) =
+    let* tag' = tag_of t in
+    if tag' = tag then body_of t else Error (Error.mismatched_tag tag tag')
+  in
+  let as_dictionary' pairs =
+    List.fold_right
+      (fun term dict ->
+        let* dict = dict in
+        match term with
+        | List [Atom k; v] -> Ok (BatMap.add k v dict)
+        | p -> Error (Error.malformed_pair p) )
+      pairs (Ok BatMap.empty)
+  in
+  strip_tag tag t |> fmap as_dictionary'
+
+let as_string = function Atom s -> Ok s | form -> Error (Error.expected_atom form)
+
+let as_int f =
+  let open Utilities.Result in
+  let* s = as_string f in
+  int_of_string_opt s |> Option.to_result ~none:(Error.not_a_number f)
-- 
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