ocamlPackages.easy-format: modernized derivation

- Removed with lib
- Added changelog and longDescription to meta
- Replaced sha256 with hash

pkgs/development/ocaml-modules/easy-format/default.nix

@@ -10,12 +10,12 @@ let
     if lib.versionAtLeast ocaml.version "4.08" then
       {
         version = "1.3.4";
-        sha256 = "sha256-Hb8FHp9oV03ebi4lSma5xSTKQl6As26Zr5btlkq2EMM=";
+        hash = "sha256-Hb8FHp9oV03ebi4lSma5xSTKQl6As26Zr5btlkq2EMM=";
       }
     else
       {
         version = "1.3.2";
-        sha256 = "sha256:09hrikx310pac2sb6jzaa7k6fmiznnmhdsqij1gawdymhawc4h1l";
+        hash = "sha256-NEDCuILVN65ekBHrBqu1P1Zn5lHqS7O0YOqCMPqMGSY=";
       };
 in
 
@@ -25,15 +25,34 @@ buildDunePackage rec {
 
   src = fetchurl {
     url = "https://github.com/ocaml-community/easy-format/releases/download/${version}/easy-format-${version}.tbz";
-    inherit (params) sha256;
+    inherit (params) hash;
   };
 
   doCheck = true;
 
-  meta = with lib; {
+  meta = {
     description = "High-level and functional interface to the Format module of the OCaml standard library";
+    longDescription = ''
+      This module offers a high-level and functional interface to the Format module of
+      the OCaml standard library. It is a pretty-printing facility, i.e. it takes as
+      input some code represented as a tree and formats this code into the most
+      visually satisfying result, breaking and indenting lines of code where
+      appropriate.
+
+      Input data must be first modelled and converted into a tree using 3 kinds of
+      nodes:
+
+      * atoms
+      * lists
+      * labelled nodes
+
+      Atoms represent any text that is guaranteed to be printed as-is. Lists can model
+      any sequence of items such as arrays of data or lists of definitions that are
+      labelled with something like "int main", "let x =" or "x:".
+    '';
     homepage = "https://github.com/ocaml-community/easy-format";
-    license = licenses.bsd3;
-    maintainers = [ maintainers.vbgl ];
+    changelog = "https://github.com/ocaml-community/easy-format/releases/tag/${params.version}";
+    license = lib.licenses.bsd3;
+    maintainers = with lib.maintainers; [ vbgl ];
   };
 }