add piston nix pkg for sbcl-lisp

runtimes/sbcl-lisp.nix

@@ -0,0 +1,32 @@
+{pkgs, piston, ...}:
+let
+    pkg = pkgs.sbcl; 
+in piston.mkRuntime {
+    language = "lisp";
+    version = pkg.version;
+    runtime = "sbcl";
+
+    aliases = [
+        "lisp"
+        "cl"
+        "commonlisp"
+    ];
+
+    run = ''
+        ${pkg}/bin/sbcl --script "$@"
+    '';
+
+    tests = [
+        (piston.mkTest {
+            files = {
+                "test.cl" = ''
+                    (write-line "OK")
+                '';
+            };
+            args = [];
+            stdin = "";
+            packages = [];
+            main = "test.cl";
+        })
+    ];
+}