* Option --argstr for passing string arguments easily. (NIX-75)

tests/lang.sh

@@ -40,7 +40,11 @@ for i in lang/eval-okay-*.nix; do
     i=$(basename $i .nix)
 
     if test -e lang/$i.exp; then
-        if ! $nixinstantiate --eval-only lang/$i.nix > lang/$i.out; then
+        flags=
+        if test -e lang/$i.flags; then
+            flags=$(cat lang/$i.flags)
+        fi
+        if ! $nixinstantiate $flags --eval-only lang/$i.nix > lang/$i.out; then
             echo "FAIL: $i should evaluate"
             fail=1
         elif ! $aterm_bin/atdiff lang/$i.out lang/$i.exp; then

tests/lang/eval-okay-autoargs.exp

@@ -0,0 +1 @@
+Str("xyzzy!xyzzy!foobar",[])

tests/lang/eval-okay-autoargs.flags

@@ -0,0 +1 @@
+--arg lib import(lang/lib.nix) --argstr xyzzy xyzzy! -A result

tests/lang/eval-okay-autoargs.nix

@@ -0,0 +1,15 @@
+let
+
+  foobar = "foobar";
+
+in
+
+{ xyzzy2 ? xyzzy # mutually recursive args
+, xyzzy ? "blaat" # will be overriden by --argstr
+, fb ? foobar
+, lib # will be set by --arg
+}:
+
+{
+  result = lib.concat [xyzzy xyzzy2 fb];
+}