Initial commit.

nixredo. No default.do resolution.

builder.nix

@@ -0,0 +1,32 @@
+builderArgs:
+let
+
+  myself = { nixpkgs ? <nixpkgs>, pkgs ? import nixpkgs {}, rargs, cwd }:
+    builder:
+    with builtins;
+    let
+      resolveLocal = arg: let
+        fullPath = cwd + "/" + arg + ".nix";
+        recurse = myself { rargs = [ (toString arg) (toString arg) ]; inherit cwd; };
+      in recurse fullPath;
+      funcPkgs = { __functor = self: arg: resolveLocal arg; } // pkgs;
+
+      _builder = if (tryEval (import builder)).success
+                 then import builder
+                 else ''
+         #!/bin/sh
+         ${builder} $1 $2 $out >$out
+       '';
+      __builder = if isFunction _builder then _builder funcPkgs
+                  else _builder;
+      args = { stdenv = pkgs.stdenvNoCC; } // (if isString __builder
+             then { builder = __builder; }
+             else  __builder);
+    in (args.deriver or args.stdenv.mkDerivation) ({
+      name = pkgs.lib.strings.sanitizeDerivationName (builtins.elemAt rargs 0);
+      buildCommand = args.builder;
+      passAsFile = [ "buildCommand" ];
+      preferLocalBuild = true;
+      allowSubstitutes = false;
+    } // (removeAttrs args [ "builder" "system" "deriver" ])); # myself
+in myself builderArgs

default.nix

@@ -0,0 +1,15 @@
+{ stdenv, jq }:
+
+stdenv.mkDerivation {
+  name = "nixredo-1";
+  phases = [ "installPhase" "fixupPhase" ];
+  jq = "${jq}/bin/jq";
+  buildernix = ./builder.nix;
+
+  installPhase = ''
+    mkdir -p $out/bin
+    cp ${./nixredo} $out/bin/nixredo
+    substituteAllInPlace $out/bin/nixredo
+    chmod +x $out/bin/nixredo
+  '';
+}

nixredo

@@ -0,0 +1,21 @@
+#!/bin/sh
+exec >&2
+[ -n "$NIXREDO_ROOT" ] || { printf "Set NIXREDO_ROOT. Set empty to use global nix store\n"; exit 127; }
+if [ $# -eq 0 ]; then set -- all; fi
+if [ -e "$1.nix" ]; then
+  set -e
+  set -- "$1" "$1" "$1.redo.tmp"
+  f=$(realpath "$1.nix")
+  out=$(nix -vL build ${NIXREDO_ROOT:+--store "$NIXREDO_ROOT"} --option auto-optimise-store true --impure --json --no-link --expr "import @buildernix@ { cwd = \"$PWD/\"; rargs = [ \"$1\" \"$1\" ];} \"$f\"" | @jq@ -r '.[0].outputs.out')
+  [ -n "$out" ] || exit 127
+  rm -rf "$1"
+  ln "${NIXREDO_ROOT+$NIXREDO_ROOT/}$out" "$3"
+  chmod +w "$3"
+  touch "$3"
+  mv "$3" "$1"
+elif [ -e "$1" ]; then
+  :
+else
+  printf "Error: No rule to build %s\n" "$1"
+  exit 127
+fi