Add wrapper scripts for node / yarn on NixOS.

nix/lib.inc.sh

@@ -0,0 +1,10 @@
+function wrap() {
+    local TOOL="$1"
+    local REPO="$2"
+    shift
+    shift
+
+    SHELL_NIX="$REPO/shell.nix"
+    QUOTED_ARGS="$(printf "${1+ %q}" "$@")"
+    exec nix-shell "$SHELL_NIX" --pure --command "$TOOL $QUOTED_ARGS"
+}

nix/node

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+REPO=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+source "$REPO/nix/lib.inc.sh"
+
+wrap node "$REPO" "$@"

nix/yarn

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+REPO=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+source "$REPO/nix/lib.inc.sh"
+
+wrap yarn "$REPO" "$@"

shell.nix

@@ -12,6 +12,7 @@ stdenv.mkDerivation rec {
     nodejs-16_x
     rsync
     sqlite
+    yarn
     zlib
   ];