Nixify C build

This is working with libsodium as an example. Its unfortunate that we need the
extra ':arg -lsodium' but how else can I get the name of the library for
linking? Is that something in the nix attr metadata? Anyway, an optimization for
another day.

2 files changed, 29 insertions, 6 deletions

diff --git a/Biz/Bild/Builder.nix b/Biz/Bild/Builder.nix
index 7ce29a2..2b62b89 100644
--- a/Biz/Bild/Builder.nix
+++ b/Biz/Bild/Builder.nix
@@ -19,6 +19,8 @@ with builtins;
 let
   srcs_ = (lib.strings.splitString " " srcs) ++ [main];
 
+  isEmpty = x: x == null || x == [];
+
   skip = ["_" ".direnv"];
   filter = file: type:
     if elem (baseNameOf file) skip then false
@@ -35,12 +37,12 @@ let
   src = lib.sources.cleanSourceWith {inherit filter; src = lib.sources.cleanSource root;};
 
   langdeps_ =
-    if langdeps == null || langdeps == [] then
+    if isEmpty langdeps then
       []
     else
       private.selectAttrs (lib.strings.splitString " " langdeps) private.${packageSet};
   sysdeps_ =
-    if sysdeps == null || sysdeps == [] then
+    if isEmpty sysdeps then
       []
     else
       private.selectAttrs (lib.strings.splitString " " sysdeps) private.nixpkgs.pkgs;
@@ -53,7 +55,6 @@ in {
     buildPhase = compileLine;
   };
 
-
   haskell = stdenv.mkDerivation rec {
     inherit name src BIZ_ROOT postUnpack;
     buildInputs = sysdeps_ ++ [
@@ -65,6 +66,19 @@ in {
     buildPhase = compileLine;
   };
 
+  c = stdenv.mkDerivation rec {
+    inherit name src BIZ_ROOT postUnpack;
+    buildInputs = langdeps_ ++ sysdeps_;
+    installPhase = "install -D ${name} $out/bin/${name}";
+    buildPhase = lib.strings.concatStringsSep " " [
+      compileLine
+      (if isEmpty langdeps then "" else
+      "$(pkg-config --cflags ${langdeps})")
+      (if isEmpty sysdeps then "" else
+      "$(pkg-config --libs ${sysdeps})")
+    ];
+  };
+
   python = buildPythonApplication rec {
     inherit name src BIZ_ROOT postUnpack;
     propagatedBuildInputs = [ (private.pythonWith (_: langdeps_)) ] ++ sysdeps_;
diff --git a/Biz/Bild/Example.c b/Biz/Bild/Example.c
index 9966dba..52ea9b9 100644
--- a/Biz/Bild/Example.c
+++ b/Biz/Bild/Example.c
@@ -1,6 +1,15 @@
-// : out helloworld.exe
-void
-main ()
+// : out examplesodium.exe
+// : dep libsodium
+// : arg -lsodium
+#include <sodium.h>
+
+int
+main (void)
 {
+  if (sodium_init () < 0)
+    {
+      /* panic! the library couldn't be initialized; it is not safe to use */
+    }
   printf ("Biz/Bild/Example.c: Hello world!\n");
+  return 0;
 }