lisp-modules: replace "_" in package names with "__" for reversibility

doc/languages-frameworks/lisp.section.md

@@ -129,6 +129,7 @@ During Quicklisp import:
 - `+` in names are converted to `_plus{_,}`: `cl+ssl`->`cl_plus_ssl`, `alexandria+`->`alexandria_plus`
 - `.` to `_dot_`: `iolib.base`->`iolib_dot_base`
 - names starting with a number have a `_` prepended (`3d-vectors`->`_3d-vectors`)
+- `_` in names is converted to `__` for reversibility
 
 
 ## Defining packages manually inside Nixpkgs

pkgs/development/lisp-modules/import/nix.lisp

@@ -41,8 +41,8 @@
 
 (defun nixify-symbol (string)
   (flet ((fix-special-chars (str)
-           (replace-regexes '("[+]$" "[+][/]" "[+]" "[.]" "[/]")
-                            '("_plus" "_plus/" "_plus_" "_dot_" "_slash_")
+           (replace-regexes '("[_]" "[+]$" "[+][/]" "[+]" "[.]" "[/]")
+                            '("__" "_plus" "_plus/" "_plus_" "_dot_" "_slash_")
                             str)))
     (if (ppcre:scan "^[0-9]" string)
         (str:concat "_" (fix-special-chars string))