diff --git a/go/cases-to-do.txt b/go/cases-to-do.txt
index e73d880f2..4220cc7ba 100644
--- a/go/cases-to-do.txt
+++ b/go/cases-to-do.txt
@@ -32,18 +32,13 @@ rrv -C20 ./reg-test/cases/case-c-dsl-local-map-variable-write-read.sh
 ================================================================
 ARRAY/MAP
 
-rrv ./reg-test/cases/case-c-localvar-unsets.sh
-
-rrv -C5 ./reg-test/cases/case-c-dsl-for-oosvar-loops.sh
+rrv ./reg-test/cases/case-c-dsl-asserting.sh
+rrv ./reg-test/cases/case-c-dsl-for-oosvar-loops.sh
+rrv ./reg-test/cases/case-c-dsl-length-depth-leafcount.sh
 rrv ./reg-test/cases/case-c-dsl-mapvar-assignments.sh
-
+rrv ./reg-test/cases/case-c-dsl-mapvar-for-loops.sh
 rrv ./reg-test/cases/case-c-dsl-split-join.sh
-rrv -C5 ./reg-test/cases/case-c-dsl-asserting.sh
-rrv -C1 ./reg-test/cases/case-c-dsl-length-depth-leafcount.sh
-* int map keys
-
-rrv -C1 ./reg-test/cases/case-c-dsl-mapvar-for-loops.sh
-* int map keys
+rrv ./reg-test/cases/case-c-localvar-unsets.sh
 
 ================================================================
 PARTIALLY IMPLEMENTED:
diff --git a/go/reg-test/cases/case-go-dsl-array-index-alias.sh b/go/reg-test/cases/case-array-map-indexing.sh
similarity index 56%
rename from go/reg-test/cases/case-go-dsl-array-index-alias.sh
rename to go/reg-test/cases/case-array-map-indexing.sh
index 342597be6..a7bafb5d0 100644
--- a/go/reg-test/cases/case-go-dsl-array-index-alias.sh
+++ b/go/reg-test/cases/case-array-map-indexing.sh
@@ -1,11 +1,74 @@
+# Right-hand sides, non-indexed
+
+run_mlr --oxtab --from reg-test/input/abixy head -n 1 then put '
+  $_1 = ""; # just for visual output-spacing
+  $srec_keyed_by_2        = $[2];
+  $srec_name_2            = $[[2]];
+  $srec_value_2           = $[[[2]]];
+  $_2 = "";
+  $dollar_star_keyed_by_2 = $*[2];
+  $dollar_star_name_2     = $*[[2]];
+  $dollar_star_value_2    = $*[[[2]]];
+  $_3 = "";
+  mymap                   = {"a":7, "b":8, "c":9};
+  $mymap_keyed_by_2       = mymap[2];
+  $mymap_name_2           = mymap[[2]];
+  $mymap_value_2          = mymap[[[2]]];
+  $_4 = "";
+  myarray                 = [7, 8, 9];
+  $myarray_keyed_by_2     = myarray[2];
+  $myarray_name_2         = myarray[[2]];
+  $myarray_value_2        = myarray[[[2]]];
+'
+
+run_mlr --oxtab --from reg-test/input/abixy head -n 1 then put '
+  $_1 = ""; # just for visual output-spacing
+  $srec_keyed_by_2        = $[900];
+  $srec_name_2            = $[[900]];
+  $srec_value_2           = $[[[900]]];
+  $_2 = "";
+  $dollar_star_keyed_by_2 = $*[900];
+  $dollar_star_name_2     = $*[[900]];
+  $dollar_star_value_2    = $*[[[900]]];
+  $_3 = "";
+  mymap                   = {"a":7, "b":8, "c":9};
+  $mymap_keyed_by_2       = mymap[900];
+  $mymap_name_2           = mymap[[900]];
+  $mymap_value_2          = mymap[[[900]]];
+  $_4 = "";
+  myarray                 = [7, 8, 9];
+  $myarray_keyed_by_2     = myarray[900];
+  $myarray_name_2         = myarray[[900]];
+  $myarray_value_2        = myarray[[[900]]];
+'
+
 run_mlr --from $indir/s.dkvp --idkvp --opprint put '$z = [$a,$b,$i,$x,$y][1]'
 run_mlr --from $indir/s.dkvp --idkvp --opprint put '$z = [$a,$b,$i,$x,$y][-1]'
 run_mlr --from $indir/s.dkvp --idkvp --opprint put '$z = [$a,$b,$i,$x,$y][NR]'
 
-run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $[NR]'
-run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $[-NR]'
-run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $*[NR]'
-run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $*[-NR]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $[NF]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $[-NF]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $*[NF]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $*[-NF]'
+
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $[[NF]]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $[[-NF]]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $*[[NF]]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $[*[-NF]]'
+
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $[[[NF]]]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $[[[-NF]]]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$up   = $*[[[NF]]]'
+run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$down = $*[[[-NF]]]'
+
+# Unsets
+
+run_mlr --opprint put 'unset $c' $indir/abixy
+run_mlr --opprint put 'unset $c; $c="new"' $indir/abixy
+run_mlr --opprint put '$c=$a.$b; unset $c; $c="new"' $indir/abixy
+run_mlr --opprint put '$c=$a.$b; unset $c' $indir/abixy
+
+# Left-hand sides, non-indexed
 
 run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$[1] = "new"'
 run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$[2] = "new"'
@@ -57,3 +120,22 @@ run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$*[[[-1]]] = "n
 run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$*[[[-2]]] = "new"'
 run_mlr --opprint --from $indir/s.dkvp --from $indir/t.dkvp put '$*[[[-5]]] = "new"'
 
+# Mix of left-hand and right-hand sides
+
+run_mlr --opprint put '$NEW = $[[3]]'     $indir/abixy
+run_mlr --opprint put '$NEW = $[[[3]]]'   $indir/abixy
+
+run_mlr --opprint put '$NEW = $[[11]]'    $indir/abixy
+run_mlr --opprint put '$NEW = $[[[11]]]'  $indir/abixy
+
+run_mlr --opprint put '$[[3]]   = "NEW"'  $indir/abixy
+run_mlr --opprint put '$[[[3]]] = "NEW"'  $indir/abixy
+
+run_mlr --opprint put '$[[11]]   = "NEW"' $indir/abixy
+run_mlr --opprint put '$[[[11]]] = "NEW"' $indir/abixy
+
+run_mlr --opprint put '$[[1]] = $[[2]]' $indir/abixy
+
+run_mlr --opprint put '$a     = $[[2]]; unset $["a"]' $indir/abixy
+run_mlr --opprint put '$[[1]] = $b;     unset $[[1]]' $indir/abixy
+run_mlr --opprint put '$[[1]] = $[[2]]; unset $["a"]' $indir/abixy
diff --git a/go/reg-test/cases/case-positional-indexing.sh b/go/reg-test/cases/case-positional-indexing.sh
deleted file mode 100644
index 9159f35d9..000000000
--- a/go/reg-test/cases/case-positional-indexing.sh
+++ /dev/null
@@ -1,64 +0,0 @@
-run_mlr --oxtab --from reg-test/input/abixy head -n 1 then put '
-  $_1 = ""; # just for visual output-spacing
-  $srec_keyed_by_2        = $[2];
-  $srec_name_2            = $[[2]];
-  $srec_value_2           = $[[[2]]];
-  $_2 = "";
-  $dollar_star_keyed_by_2 = $*[2];
-  $dollar_star_name_2     = $*[[2]];
-  $dollar_star_value_2    = $*[[[2]]];
-  $_3 = "";
-  mymap                   = {"a":7, "b":8, "c":9};
-  $mymap_keyed_by_2       = mymap[2];
-  $mymap_name_2           = mymap[[2]];
-  $mymap_value_2          = mymap[[[2]]];
-  $_4 = "";
-  myarray                 = [7, 8, 9];
-  $myarray_keyed_by_2     = myarray[2];
-  $myarray_name_2         = myarray[[2]];
-  $myarray_value_2        = myarray[[[2]]];
-'
-
-run_mlr --oxtab --from reg-test/input/abixy head -n 1 then put '
-  $_1 = ""; # just for visual output-spacing
-  $srec_keyed_by_2        = $[900];
-  $srec_name_2            = $[[900]];
-  $srec_value_2           = $[[[900]]];
-  $_2 = "";
-  $dollar_star_keyed_by_2 = $*[900];
-  $dollar_star_name_2     = $*[[900]];
-  $dollar_star_value_2    = $*[[[900]]];
-  $_3 = "";
-  mymap                   = {"a":7, "b":8, "c":9};
-  $mymap_keyed_by_2       = mymap[900];
-  $mymap_name_2           = mymap[[900]];
-  $mymap_value_2          = mymap[[[900]]];
-  $_4 = "";
-  myarray                 = [7, 8, 9];
-  $myarray_keyed_by_2     = myarray[900];
-  $myarray_name_2         = myarray[[900]];
-  $myarray_value_2        = myarray[[[900]]];
-'
-
-run_mlr --opprint put '$NEW = $[[3]]'     $indir/abixy
-run_mlr --opprint put '$NEW = $[[[3]]]'   $indir/abixy
-
-run_mlr --opprint put '$NEW = $[[11]]'    $indir/abixy
-run_mlr --opprint put '$NEW = $[[[11]]]'  $indir/abixy
-
-run_mlr --opprint put '$[[3]]   = "NEW"'  $indir/abixy
-run_mlr --opprint put '$[[[3]]] = "NEW"'  $indir/abixy
-
-run_mlr --opprint put '$[[11]]   = "NEW"' $indir/abixy
-run_mlr --opprint put '$[[[11]]] = "NEW"' $indir/abixy
-
-run_mlr --opprint put '$[[1]] = $[[2]]' $indir/abixy
-
-run_mlr --opprint put '$a     = $[[2]]; unset $["a"]' $indir/abixy
-run_mlr --opprint put '$[[1]] = $b;     unset $[[1]]' $indir/abixy
-run_mlr --opprint put '$[[1]] = $[[2]]; unset $["a"]' $indir/abixy
-
-run_mlr --opprint put 'unset $c' $indir/abixy
-run_mlr --opprint put 'unset $c; $c="new"' $indir/abixy
-run_mlr --opprint put '$c=$a.$b; unset $c; $c="new"' $indir/abixy
-run_mlr --opprint put '$c=$a.$b; unset $c' $indir/abixy
diff --git a/go/reg-test/expected/case-go-dsl-array-index-alias.sh.err b/go/reg-test/expected/case-array-map-indexing.sh.err
similarity index 100%
rename from go/reg-test/expected/case-go-dsl-array-index-alias.sh.err
rename to go/reg-test/expected/case-array-map-indexing.sh.err
diff --git a/go/reg-test/expected/case-array-map-indexing.sh.out b/go/reg-test/expected/case-array-map-indexing.sh.out
new file mode 100644
index 000000000..98247d80c
--- /dev/null
+++ b/go/reg-test/expected/case-array-map-indexing.sh.out
@@ -0,0 +1,778 @@
+
+mlr --oxtab --from reg-test/input/abixy head -n 1 then put 
+  $_1 = ""; # just for visual output-spacing
+  $srec_keyed_by_2        = $[2];
+  $srec_name_2            = $[[2]];
+  $srec_value_2           = $[[[2]]];
+  $_2 = "";
+  $dollar_star_keyed_by_2 = $*[2];
+  $dollar_star_name_2     = $*[[2]];
+  $dollar_star_value_2    = $*[[[2]]];
+  $_3 = "";
+  mymap                   = {"a":7, "b":8, "c":9};
+  $mymap_keyed_by_2       = mymap[2];
+  $mymap_name_2           = mymap[[2]];
+  $mymap_value_2          = mymap[[[2]]];
+  $_4 = "";
+  myarray                 = [7, 8, 9];
+  $myarray_keyed_by_2     = myarray[2];
+  $myarray_name_2         = myarray[[2]];
+  $myarray_value_2        = myarray[[[2]]];
+
+a                   pan
+b                   pan
+i                   1
+x                   0.3467901443380824
+y                   0.7268028627434533
+_1                  
+srec_name_2         b
+srec_value_2        pan
+_2                  
+dollar_star_name_2  b
+dollar_star_value_2 pan
+_3                  
+mymap_name_2        b
+mymap_value_2       8
+_4                  
+myarray_keyed_by_2  8
+myarray_name_2      2
+myarray_value_2     8
+
+mlr --oxtab --from reg-test/input/abixy head -n 1 then put 
+  $_1 = ""; # just for visual output-spacing
+  $srec_keyed_by_2        = $[900];
+  $srec_name_2            = $[[900]];
+  $srec_value_2           = $[[[900]]];
+  $_2 = "";
+  $dollar_star_keyed_by_2 = $*[900];
+  $dollar_star_name_2     = $*[[900]];
+  $dollar_star_value_2    = $*[[[900]]];
+  $_3 = "";
+  mymap                   = {"a":7, "b":8, "c":9};
+  $mymap_keyed_by_2       = mymap[900];
+  $mymap_name_2           = mymap[[900]];
+  $mymap_value_2          = mymap[[[900]]];
+  $_4 = "";
+  myarray                 = [7, 8, 9];
+  $myarray_keyed_by_2     = myarray[900];
+  $myarray_name_2         = myarray[[900]];
+  $myarray_value_2        = myarray[[[900]]];
+
+a  pan
+b  pan
+i  1
+x  0.3467901443380824
+y  0.7268028627434533
+_1 
+_2 
+_3 
+_4 
+
+mlr --from ./reg-test/input/s.dkvp --idkvp --opprint put $z = [$a,$b,$i,$x,$y][1]
+a   b   i x                   y                   z
+pan pan 1 0.3467901443380824  0.7268028627434533  pan
+eks pan 2 0.7586799647899636  0.5221511083334797  eks
+wye wye 3 0.20460330576630303 0.33831852551664776 wye
+eks wye 4 0.38139939387114097 0.13418874328430463 eks
+
+mlr --from ./reg-test/input/s.dkvp --idkvp --opprint put $z = [$a,$b,$i,$x,$y][-1]
+a   b   i x                   y                   z
+pan pan 1 0.3467901443380824  0.7268028627434533  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463 0.13418874328430463
+
+mlr --from ./reg-test/input/s.dkvp --idkvp --opprint put $z = [$a,$b,$i,$x,$y][NR]
+a   b   i x                   y                   z
+pan pan 1 0.3467901443380824  0.7268028627434533  pan
+eks pan 2 0.7586799647899636  0.5221511083334797  pan
+wye wye 3 0.20460330576630303 0.33831852551664776 3
+eks wye 4 0.38139939387114097 0.13418874328430463 0.38139939387114097
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $[NF]
+a   b   i x                   y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $[-NF]
+a   b   i x                   y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $*[NF]
+a   b   i x                   y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $*[-NF]
+a   b   i x                   y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $[[NF]]
+a   b   i x                   y                   up
+pan pan 1 0.3467901443380824  0.7268028627434533  y
+eks pan 2 0.7586799647899636  0.5221511083334797  y
+wye wye 3 0.20460330576630303 0.33831852551664776 y
+eks wye 4 0.38139939387114097 0.13418874328430463 y
+wye pan 5 0.5732889198020006  0.8636244699032729  y
+zee pan 6 0.5271261600918548  0.49322128674835697 y
+eks zee 7 0.6117840605678454  0.1878849191181694  y
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $[[-NF]]
+a   b   i x                   y                   down
+pan pan 1 0.3467901443380824  0.7268028627434533  a
+eks pan 2 0.7586799647899636  0.5221511083334797  a
+wye wye 3 0.20460330576630303 0.33831852551664776 a
+eks wye 4 0.38139939387114097 0.13418874328430463 a
+wye pan 5 0.5732889198020006  0.8636244699032729  a
+zee pan 6 0.5271261600918548  0.49322128674835697 a
+eks zee 7 0.6117840605678454  0.1878849191181694  a
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $*[[NF]]
+a   b   i x                   y                   up
+pan pan 1 0.3467901443380824  0.7268028627434533  y
+eks pan 2 0.7586799647899636  0.5221511083334797  y
+wye wye 3 0.20460330576630303 0.33831852551664776 y
+eks wye 4 0.38139939387114097 0.13418874328430463 y
+wye pan 5 0.5732889198020006  0.8636244699032729  y
+zee pan 6 0.5271261600918548  0.49322128674835697 y
+eks zee 7 0.6117840605678454  0.1878849191181694  y
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $[*[-NF]]
+Exit status was 1; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $[[[NF]]]
+a   b   i x                   y                   up
+pan pan 1 0.3467901443380824  0.7268028627434533  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697 0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $[[[-NF]]]
+a   b   i x                   y                   down
+pan pan 1 0.3467901443380824  0.7268028627434533  pan
+eks pan 2 0.7586799647899636  0.5221511083334797  eks
+wye wye 3 0.20460330576630303 0.33831852551664776 wye
+eks wye 4 0.38139939387114097 0.13418874328430463 eks
+wye pan 5 0.5732889198020006  0.8636244699032729  wye
+zee pan 6 0.5271261600918548  0.49322128674835697 zee
+eks zee 7 0.6117840605678454  0.1878849191181694  eks
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $*[[[NF]]]
+a   b   i x                   y                   up
+pan pan 1 0.3467901443380824  0.7268028627434533  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697 0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $*[[[-NF]]]
+a   b   i x                   y                   down
+pan pan 1 0.3467901443380824  0.7268028627434533  pan
+eks pan 2 0.7586799647899636  0.5221511083334797  eks
+wye wye 3 0.20460330576630303 0.33831852551664776 wye
+eks wye 4 0.38139939387114097 0.13418874328430463 eks
+wye pan 5 0.5732889198020006  0.8636244699032729  wye
+zee pan 6 0.5271261600918548  0.49322128674835697 zee
+eks zee 7 0.6117840605678454  0.1878849191181694  eks
+
+mlr --opprint put unset $c ./reg-test/input/abixy
+a   b   i  x                   y
+pan pan 1  0.3467901443380824  0.7268028627434533
+eks pan 2  0.7586799647899636  0.5221511083334797
+wye wye 3  0.20460330576630303 0.33831852551664776
+eks wye 4  0.38139939387114097 0.13418874328430463
+wye pan 5  0.5732889198020006  0.8636244699032729
+zee pan 6  0.5271261600918548  0.49322128674835697
+eks zee 7  0.6117840605678454  0.1878849191181694
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put unset $c; $c="new" ./reg-test/input/abixy
+a   b   i  x                   y                   c
+pan pan 1  0.3467901443380824  0.7268028627434533  new
+eks pan 2  0.7586799647899636  0.5221511083334797  new
+wye wye 3  0.20460330576630303 0.33831852551664776 new
+eks wye 4  0.38139939387114097 0.13418874328430463 new
+wye pan 5  0.5732889198020006  0.8636244699032729  new
+zee pan 6  0.5271261600918548  0.49322128674835697 new
+eks zee 7  0.6117840605678454  0.1878849191181694  new
+zee wye 8  0.5985540091064224  0.976181385699006   new
+hat wye 9  0.03144187646093577 0.7495507603507059  new
+pan wye 10 0.5026260055412137  0.9526183602969864  new
+
+mlr --opprint put $c=$a.$b; unset $c; $c="new" ./reg-test/input/abixy
+a   b   i  x                   y                   c
+pan pan 1  0.3467901443380824  0.7268028627434533  new
+eks pan 2  0.7586799647899636  0.5221511083334797  new
+wye wye 3  0.20460330576630303 0.33831852551664776 new
+eks wye 4  0.38139939387114097 0.13418874328430463 new
+wye pan 5  0.5732889198020006  0.8636244699032729  new
+zee pan 6  0.5271261600918548  0.49322128674835697 new
+eks zee 7  0.6117840605678454  0.1878849191181694  new
+zee wye 8  0.5985540091064224  0.976181385699006   new
+hat wye 9  0.03144187646093577 0.7495507603507059  new
+pan wye 10 0.5026260055412137  0.9526183602969864  new
+
+mlr --opprint put $c=$a.$b; unset $c ./reg-test/input/abixy
+a   b   i  x                   y
+pan pan 1  0.3467901443380824  0.7268028627434533
+eks pan 2  0.7586799647899636  0.5221511083334797
+wye wye 3  0.20460330576630303 0.33831852551664776
+eks wye 4  0.38139939387114097 0.13418874328430463
+wye pan 5  0.5732889198020006  0.8636244699032729
+zee pan 6  0.5271261600918548  0.49322128674835697
+eks zee 7  0.6117840605678454  0.1878849191181694
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[1] = "new"
+a   b   i x                   y                   1
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[2] = "new"
+a   b   i x                   y                   2
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[5] = "new"
+a   b   i x                   y                   5
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-1] = "new"
+a   b   i x                   y                   -1
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-2] = "new"
+a   b   i x                   y                   -2
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-5] = "new"
+a   b   i x                   y                   -5
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put @idx = NR % 5; @idx = @idx == 0 ? 5 : @idx; $[@idx] = "NEW"
+a   b   i x                  y                  1
+pan pan 1 0.3467901443380824 0.7268028627434533 NEW
+
+a   b   i x                  y                  2
+eks pan 2 0.7586799647899636 0.5221511083334797 NEW
+
+a   b   i x                   y                   3
+wye wye 3 0.20460330576630303 0.33831852551664776 NEW
+
+a   b   i x                   y                   4
+eks wye 4 0.38139939387114097 0.13418874328430463 NEW
+
+a   b   i x                  y                  5
+wye pan 5 0.5732889198020006 0.8636244699032729 NEW
+
+a   b   i x                  y                   1
+zee pan 6 0.5271261600918548 0.49322128674835697 NEW
+
+a   b   i x                  y                  2
+eks zee 7 0.6117840605678454 0.1878849191181694 NEW
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[1]       = "new"
+a   b   i x                   y                   1
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[2]       = "new"
+a   b   i x                   y                   2
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[5]       = "new"
+a   b   i x                   y                   5
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-1]      = "new"
+a   b   i x                   y                   -1
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-2]      = "new"
+a   b   i x                   y                   -2
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-5]      = "new"
+a   b   i x                   y                   -5
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[1]]     = "new"
+new b   i x                   y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[2]]     = "new"
+a   new i x                   y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[5]]     = "new"
+a   b   i x                   new
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[-1]]    = "new"
+a   b   i x                   new
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[-2]]    = "new"
+a   b   i new                 y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[-5]]    = "new"
+new b   i x                   y
+pan pan 1 0.3467901443380824  0.7268028627434533
+eks pan 2 0.7586799647899636  0.5221511083334797
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+wye pan 5 0.5732889198020006  0.8636244699032729
+zee pan 6 0.5271261600918548  0.49322128674835697
+eks zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[[1]]]   = "new"
+a   b   i x                   y
+new pan 1 0.3467901443380824  0.7268028627434533
+new pan 2 0.7586799647899636  0.5221511083334797
+new wye 3 0.20460330576630303 0.33831852551664776
+new wye 4 0.38139939387114097 0.13418874328430463
+new pan 5 0.5732889198020006  0.8636244699032729
+new pan 6 0.5271261600918548  0.49322128674835697
+new zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[[2]]]   = "new"
+a   b   i x                   y
+pan new 1 0.3467901443380824  0.7268028627434533
+eks new 2 0.7586799647899636  0.5221511083334797
+wye new 3 0.20460330576630303 0.33831852551664776
+eks new 4 0.38139939387114097 0.13418874328430463
+wye new 5 0.5732889198020006  0.8636244699032729
+zee new 6 0.5271261600918548  0.49322128674835697
+eks new 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[[5]]]   = "new"
+a   b   i x                   y
+pan pan 1 0.3467901443380824  new
+eks pan 2 0.7586799647899636  new
+wye wye 3 0.20460330576630303 new
+eks wye 4 0.38139939387114097 new
+wye pan 5 0.5732889198020006  new
+zee pan 6 0.5271261600918548  new
+eks zee 7 0.6117840605678454  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[[-1]]]  = "new"
+a   b   i x                   y
+pan pan 1 0.3467901443380824  new
+eks pan 2 0.7586799647899636  new
+wye wye 3 0.20460330576630303 new
+eks wye 4 0.38139939387114097 new
+wye pan 5 0.5732889198020006  new
+zee pan 6 0.5271261600918548  new
+eks zee 7 0.6117840605678454  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[[-2]]]  = "new"
+a   b   i x   y
+pan pan 1 new 0.7268028627434533
+eks pan 2 new 0.5221511083334797
+wye wye 3 new 0.33831852551664776
+eks wye 4 new 0.13418874328430463
+wye pan 5 new 0.8636244699032729
+zee pan 6 new 0.49322128674835697
+eks zee 7 new 0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[[[-5]]]  = "new"
+a   b   i x                   y
+new pan 1 0.3467901443380824  0.7268028627434533
+new pan 2 0.7586799647899636  0.5221511083334797
+new wye 3 0.20460330576630303 0.33831852551664776
+new wye 4 0.38139939387114097 0.13418874328430463
+new pan 5 0.5732889198020006  0.8636244699032729
+new pan 6 0.5271261600918548  0.49322128674835697
+new zee 7 0.6117840605678454  0.1878849191181694
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[1]      = "new"
+a   b   i x                   y                   1
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[2]      = "new"
+a   b   i x                   y                   2
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[5]      = "new"
+a   b   i x                   y                   5
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[-1]     = "new"
+a   b   i x                   y                   -1
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[-2]     = "new"
+a   b   i x                   y                   -2
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[-5]     = "new"
+a   b   i x                   y                   -5
+pan pan 1 0.3467901443380824  0.7268028627434533  new
+eks pan 2 0.7586799647899636  0.5221511083334797  new
+wye wye 3 0.20460330576630303 0.33831852551664776 new
+eks wye 4 0.38139939387114097 0.13418874328430463 new
+wye pan 5 0.5732889198020006  0.8636244699032729  new
+zee pan 6 0.5271261600918548  0.49322128674835697 new
+eks zee 7 0.6117840605678454  0.1878849191181694  new
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[1]]    = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[2]]    = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[5]]    = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[-1]]   = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[-2]]   = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[-5]]   = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[[1]]]  = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[[2]]]  = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[[5]]]  = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[[-1]]] = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[[-2]]] = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[[[-5]]] = "new"
+Exit status was 2; expected 0.
+
+mlr --opprint put $NEW = $[[3]] ./reg-test/input/abixy
+a   b   i  x                   y                   NEW
+pan pan 1  0.3467901443380824  0.7268028627434533  i
+eks pan 2  0.7586799647899636  0.5221511083334797  i
+wye wye 3  0.20460330576630303 0.33831852551664776 i
+eks wye 4  0.38139939387114097 0.13418874328430463 i
+wye pan 5  0.5732889198020006  0.8636244699032729  i
+zee pan 6  0.5271261600918548  0.49322128674835697 i
+eks zee 7  0.6117840605678454  0.1878849191181694  i
+zee wye 8  0.5985540091064224  0.976181385699006   i
+hat wye 9  0.03144187646093577 0.7495507603507059  i
+pan wye 10 0.5026260055412137  0.9526183602969864  i
+
+mlr --opprint put $NEW = $[[[3]]] ./reg-test/input/abixy
+a   b   i  x                   y                   NEW
+pan pan 1  0.3467901443380824  0.7268028627434533  1
+eks pan 2  0.7586799647899636  0.5221511083334797  2
+wye wye 3  0.20460330576630303 0.33831852551664776 3
+eks wye 4  0.38139939387114097 0.13418874328430463 4
+wye pan 5  0.5732889198020006  0.8636244699032729  5
+zee pan 6  0.5271261600918548  0.49322128674835697 6
+eks zee 7  0.6117840605678454  0.1878849191181694  7
+zee wye 8  0.5985540091064224  0.976181385699006   8
+hat wye 9  0.03144187646093577 0.7495507603507059  9
+pan wye 10 0.5026260055412137  0.9526183602969864  10
+
+mlr --opprint put $NEW = $[[11]] ./reg-test/input/abixy
+a   b   i  x                   y
+pan pan 1  0.3467901443380824  0.7268028627434533
+eks pan 2  0.7586799647899636  0.5221511083334797
+wye wye 3  0.20460330576630303 0.33831852551664776
+eks wye 4  0.38139939387114097 0.13418874328430463
+wye pan 5  0.5732889198020006  0.8636244699032729
+zee pan 6  0.5271261600918548  0.49322128674835697
+eks zee 7  0.6117840605678454  0.1878849191181694
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $NEW = $[[[11]]] ./reg-test/input/abixy
+a   b   i  x                   y
+pan pan 1  0.3467901443380824  0.7268028627434533
+eks pan 2  0.7586799647899636  0.5221511083334797
+wye wye 3  0.20460330576630303 0.33831852551664776
+eks wye 4  0.38139939387114097 0.13418874328430463
+wye pan 5  0.5732889198020006  0.8636244699032729
+zee pan 6  0.5271261600918548  0.49322128674835697
+eks zee 7  0.6117840605678454  0.1878849191181694
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $[[3]]   = "NEW" ./reg-test/input/abixy
+a   b   NEW x                   y
+pan pan 1   0.3467901443380824  0.7268028627434533
+eks pan 2   0.7586799647899636  0.5221511083334797
+wye wye 3   0.20460330576630303 0.33831852551664776
+eks wye 4   0.38139939387114097 0.13418874328430463
+wye pan 5   0.5732889198020006  0.8636244699032729
+zee pan 6   0.5271261600918548  0.49322128674835697
+eks zee 7   0.6117840605678454  0.1878849191181694
+zee wye 8   0.5985540091064224  0.976181385699006
+hat wye 9   0.03144187646093577 0.7495507603507059
+pan wye 10  0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $[[[3]]] = "NEW" ./reg-test/input/abixy
+a   b   i   x                   y
+pan pan NEW 0.3467901443380824  0.7268028627434533
+eks pan NEW 0.7586799647899636  0.5221511083334797
+wye wye NEW 0.20460330576630303 0.33831852551664776
+eks wye NEW 0.38139939387114097 0.13418874328430463
+wye pan NEW 0.5732889198020006  0.8636244699032729
+zee pan NEW 0.5271261600918548  0.49322128674835697
+eks zee NEW 0.6117840605678454  0.1878849191181694
+zee wye NEW 0.5985540091064224  0.976181385699006
+hat wye NEW 0.03144187646093577 0.7495507603507059
+pan wye NEW 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $[[11]]   = "NEW" ./reg-test/input/abixy
+a   b   i  x                   y
+pan pan 1  0.3467901443380824  0.7268028627434533
+eks pan 2  0.7586799647899636  0.5221511083334797
+wye wye 3  0.20460330576630303 0.33831852551664776
+eks wye 4  0.38139939387114097 0.13418874328430463
+wye pan 5  0.5732889198020006  0.8636244699032729
+zee pan 6  0.5271261600918548  0.49322128674835697
+eks zee 7  0.6117840605678454  0.1878849191181694
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $[[[11]]] = "NEW" ./reg-test/input/abixy
+a   b   i  x                   y
+pan pan 1  0.3467901443380824  0.7268028627434533
+eks pan 2  0.7586799647899636  0.5221511083334797
+wye wye 3  0.20460330576630303 0.33831852551664776
+eks wye 4  0.38139939387114097 0.13418874328430463
+wye pan 5  0.5732889198020006  0.8636244699032729
+zee pan 6  0.5271261600918548  0.49322128674835697
+eks zee 7  0.6117840605678454  0.1878849191181694
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $[[1]] = $[[2]] ./reg-test/input/abixy
+b   b   i  x                   y
+pan pan 1  0.3467901443380824  0.7268028627434533
+eks pan 2  0.7586799647899636  0.5221511083334797
+wye wye 3  0.20460330576630303 0.33831852551664776
+eks wye 4  0.38139939387114097 0.13418874328430463
+wye pan 5  0.5732889198020006  0.8636244699032729
+zee pan 6  0.5271261600918548  0.49322128674835697
+eks zee 7  0.6117840605678454  0.1878849191181694
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $a     = $[[2]]; unset $["a"] ./reg-test/input/abixy
+b   i  x                   y
+pan 1  0.3467901443380824  0.7268028627434533
+pan 2  0.7586799647899636  0.5221511083334797
+wye 3  0.20460330576630303 0.33831852551664776
+wye 4  0.38139939387114097 0.13418874328430463
+pan 5  0.5732889198020006  0.8636244699032729
+pan 6  0.5271261600918548  0.49322128674835697
+zee 7  0.6117840605678454  0.1878849191181694
+wye 8  0.5985540091064224  0.976181385699006
+wye 9  0.03144187646093577 0.7495507603507059
+wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $[[1]] = $b;     unset $[[1]] ./reg-test/input/abixy
+pan b   i x                  y
+pan pan 1 0.3467901443380824 0.7268028627434533
+eks pan 2 0.7586799647899636 0.5221511083334797
+
+wye b   i x                   y
+wye wye 3 0.20460330576630303 0.33831852551664776
+eks wye 4 0.38139939387114097 0.13418874328430463
+
+pan b   i x                  y
+wye pan 5 0.5732889198020006 0.8636244699032729
+zee pan 6 0.5271261600918548 0.49322128674835697
+
+zee b   i x                  y
+eks zee 7 0.6117840605678454 0.1878849191181694
+
+wye b   i  x                   y
+zee wye 8  0.5985540091064224  0.976181385699006
+hat wye 9  0.03144187646093577 0.7495507603507059
+pan wye 10 0.5026260055412137  0.9526183602969864
+
+mlr --opprint put $[[1]] = $[[2]]; unset $["a"] ./reg-test/input/abixy
+b   i  x                   y
+pan 1  0.3467901443380824  0.7268028627434533
+pan 2  0.7586799647899636  0.5221511083334797
+wye 3  0.20460330576630303 0.33831852551664776
+wye 4  0.38139939387114097 0.13418874328430463
+pan 5  0.5732889198020006  0.8636244699032729
+pan 6  0.5271261600918548  0.49322128674835697
+zee 7  0.6117840605678454  0.1878849191181694
+wye 8  0.5985540091064224  0.976181385699006
+wye 9  0.03144187646093577 0.7495507603507059
+wye 10 0.5026260055412137  0.9526183602969864
+
diff --git a/go/reg-test/expected/case-go-dsl-array-index-alias.sh.out b/go/reg-test/expected/case-go-dsl-array-index-alias.sh.out
deleted file mode 100644
index b3408bb68..000000000
--- a/go/reg-test/expected/case-go-dsl-array-index-alias.sh.out
+++ /dev/null
@@ -1,210 +0,0 @@
-
-mlr --from ./reg-test/input/s.dkvp --idkvp --opprint put $z = [$a,$b,$i,$x,$y][1]
-a   b   i x                   y                   z
-pan pan 1 0.3467901443380824  0.7268028627434533  pan
-eks pan 2 0.7586799647899636  0.5221511083334797  eks
-wye wye 3 0.20460330576630303 0.33831852551664776 wye
-eks wye 4 0.38139939387114097 0.13418874328430463 eks
-
-mlr --from ./reg-test/input/s.dkvp --idkvp --opprint put $z = [$a,$b,$i,$x,$y][-1]
-a   b   i x                   y                   z
-pan pan 1 0.3467901443380824  0.7268028627434533  0.7268028627434533
-eks pan 2 0.7586799647899636  0.5221511083334797  0.5221511083334797
-wye wye 3 0.20460330576630303 0.33831852551664776 0.33831852551664776
-eks wye 4 0.38139939387114097 0.13418874328430463 0.13418874328430463
-
-mlr --from ./reg-test/input/s.dkvp --idkvp --opprint put $z = [$a,$b,$i,$x,$y][NR]
-a   b   i x                   y                   z
-pan pan 1 0.3467901443380824  0.7268028627434533  pan
-eks pan 2 0.7586799647899636  0.5221511083334797  pan
-wye wye 3 0.20460330576630303 0.33831852551664776 3
-eks wye 4 0.38139939387114097 0.13418874328430463 0.38139939387114097
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $[NR]
-a   b   i x                   y                   up
-pan pan 1 0.3467901443380824  0.7268028627434533  pan
-eks pan 2 0.7586799647899636  0.5221511083334797  pan
-wye wye 3 0.20460330576630303 0.33831852551664776 3
-eks wye 4 0.38139939387114097 0.13418874328430463 0.38139939387114097
-wye pan 5 0.5732889198020006  0.8636244699032729  0.8636244699032729
-
-a   b   i x                  y
-zee pan 6 0.5271261600918548 0.49322128674835697
-eks zee 7 0.6117840605678454 0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $[-NR]
-a   b   i x                   y                   down
-pan pan 1 0.3467901443380824  0.7268028627434533  0.7268028627434533
-eks pan 2 0.7586799647899636  0.5221511083334797  0.7586799647899636
-wye wye 3 0.20460330576630303 0.33831852551664776 3
-eks wye 4 0.38139939387114097 0.13418874328430463 wye
-wye pan 5 0.5732889198020006  0.8636244699032729  wye
-
-a   b   i x                  y
-zee pan 6 0.5271261600918548 0.49322128674835697
-eks zee 7 0.6117840605678454 0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $up   = $*[NR]
-a   b   i x                   y                   up
-pan pan 1 0.3467901443380824  0.7268028627434533  pan
-eks pan 2 0.7586799647899636  0.5221511083334797  pan
-wye wye 3 0.20460330576630303 0.33831852551664776 3
-eks wye 4 0.38139939387114097 0.13418874328430463 0.38139939387114097
-wye pan 5 0.5732889198020006  0.8636244699032729  0.8636244699032729
-
-a   b   i x                  y
-zee pan 6 0.5271261600918548 0.49322128674835697
-eks zee 7 0.6117840605678454 0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $down = $*[-NR]
-a   b   i x                   y                   down
-pan pan 1 0.3467901443380824  0.7268028627434533  0.7268028627434533
-eks pan 2 0.7586799647899636  0.5221511083334797  0.7586799647899636
-wye wye 3 0.20460330576630303 0.33831852551664776 3
-eks wye 4 0.38139939387114097 0.13418874328430463 wye
-wye pan 5 0.5732889198020006  0.8636244699032729  wye
-
-a   b   i x                  y
-zee pan 6 0.5271261600918548 0.49322128674835697
-eks zee 7 0.6117840605678454 0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[1] = "new"
-a   b   i x                   y
-new pan 1 0.3467901443380824  0.7268028627434533
-new pan 2 0.7586799647899636  0.5221511083334797
-new wye 3 0.20460330576630303 0.33831852551664776
-new wye 4 0.38139939387114097 0.13418874328430463
-new pan 5 0.5732889198020006  0.8636244699032729
-new pan 6 0.5271261600918548  0.49322128674835697
-new zee 7 0.6117840605678454  0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[2] = "new"
-a   b   i x                   y
-pan new 1 0.3467901443380824  0.7268028627434533
-eks new 2 0.7586799647899636  0.5221511083334797
-wye new 3 0.20460330576630303 0.33831852551664776
-eks new 4 0.38139939387114097 0.13418874328430463
-wye new 5 0.5732889198020006  0.8636244699032729
-zee new 6 0.5271261600918548  0.49322128674835697
-eks new 7 0.6117840605678454  0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[5] = "new"
-a   b   i x                   y
-pan pan 1 0.3467901443380824  new
-eks pan 2 0.7586799647899636  new
-wye wye 3 0.20460330576630303 new
-eks wye 4 0.38139939387114097 new
-wye pan 5 0.5732889198020006  new
-zee pan 6 0.5271261600918548  new
-eks zee 7 0.6117840605678454  new
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-1] = "new"
-a   b   i x                   y
-pan pan 1 0.3467901443380824  new
-eks pan 2 0.7586799647899636  new
-wye wye 3 0.20460330576630303 new
-eks wye 4 0.38139939387114097 new
-wye pan 5 0.5732889198020006  new
-zee pan 6 0.5271261600918548  new
-eks zee 7 0.6117840605678454  new
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-2] = "new"
-a   b   i x   y
-pan pan 1 new 0.7268028627434533
-eks pan 2 new 0.5221511083334797
-wye wye 3 new 0.33831852551664776
-eks wye 4 new 0.13418874328430463
-wye pan 5 new 0.8636244699032729
-zee pan 6 new 0.49322128674835697
-eks zee 7 new 0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $[-5] = "new"
-a   b   i x                   y
-new pan 1 0.3467901443380824  0.7268028627434533
-new pan 2 0.7586799647899636  0.5221511083334797
-new wye 3 0.20460330576630303 0.33831852551664776
-new wye 4 0.38139939387114097 0.13418874328430463
-new pan 5 0.5732889198020006  0.8636244699032729
-new pan 6 0.5271261600918548  0.49322128674835697
-new zee 7 0.6117840605678454  0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put @idx = NR % 5; @idx = @idx == 0 ? 5 : @idx; $[@idx] = "NEW"
-a   b   i   x                   y
-NEW pan 1   0.3467901443380824  0.7268028627434533
-eks NEW 2   0.7586799647899636  0.5221511083334797
-wye wye NEW 0.20460330576630303 0.33831852551664776
-eks wye 4   NEW                 0.13418874328430463
-wye pan 5   0.5732889198020006  NEW
-NEW pan 6   0.5271261600918548  0.49322128674835697
-eks NEW 7   0.6117840605678454  0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[1] = "new"
-a   b   i x                   y
-new pan 1 0.3467901443380824  0.7268028627434533
-new pan 2 0.7586799647899636  0.5221511083334797
-new wye 3 0.20460330576630303 0.33831852551664776
-new wye 4 0.38139939387114097 0.13418874328430463
-new pan 5 0.5732889198020006  0.8636244699032729
-new pan 6 0.5271261600918548  0.49322128674835697
-new zee 7 0.6117840605678454  0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[2] = "new"
-a   b   i x                   y
-pan new 1 0.3467901443380824  0.7268028627434533
-eks new 2 0.7586799647899636  0.5221511083334797
-wye new 3 0.20460330576630303 0.33831852551664776
-eks new 4 0.38139939387114097 0.13418874328430463
-wye new 5 0.5732889198020006  0.8636244699032729
-zee new 6 0.5271261600918548  0.49322128674835697
-eks new 7 0.6117840605678454  0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[5] = "new"
-a   b   i x                   y
-pan pan 1 0.3467901443380824  new
-eks pan 2 0.7586799647899636  new
-wye wye 3 0.20460330576630303 new
-eks wye 4 0.38139939387114097 new
-wye pan 5 0.5732889198020006  new
-zee pan 6 0.5271261600918548  new
-eks zee 7 0.6117840605678454  new
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[-1] = "new"
-a   b   i x                   y
-pan pan 1 0.3467901443380824  new
-eks pan 2 0.7586799647899636  new
-wye wye 3 0.20460330576630303 new
-eks wye 4 0.38139939387114097 new
-wye pan 5 0.5732889198020006  new
-zee pan 6 0.5271261600918548  new
-eks zee 7 0.6117840605678454  new
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[-2] = "new"
-a   b   i x   y
-pan pan 1 new 0.7268028627434533
-eks pan 2 new 0.5221511083334797
-wye wye 3 new 0.33831852551664776
-eks wye 4 new 0.13418874328430463
-wye pan 5 new 0.8636244699032729
-zee pan 6 new 0.49322128674835697
-eks zee 7 new 0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put $*[-5] = "new"
-a   b   i x                   y
-new pan 1 0.3467901443380824  0.7268028627434533
-new pan 2 0.7586799647899636  0.5221511083334797
-new wye 3 0.20460330576630303 0.33831852551664776
-new wye 4 0.38139939387114097 0.13418874328430463
-new pan 5 0.5732889198020006  0.8636244699032729
-new pan 6 0.5271261600918548  0.49322128674835697
-new zee 7 0.6117840605678454  0.1878849191181694
-
-mlr --opprint --from ./reg-test/input/s.dkvp --from ./reg-test/input/t.dkvp put @idx = NR % 5; @idx = @idx == 0 ? 5 : @idx; $*[@idx] = "NEW"
-a   b   i   x                   y
-NEW pan 1   0.3467901443380824  0.7268028627434533
-eks NEW 2   0.7586799647899636  0.5221511083334797
-wye wye NEW 0.20460330576630303 0.33831852551664776
-eks wye 4   NEW                 0.13418874328430463
-wye pan 5   0.5732889198020006  NEW
-NEW pan 6   0.5271261600918548  0.49322128674835697
-eks NEW 7   0.6117840605678454  0.1878849191181694
-
diff --git a/go/reg-test/expected/case-positional-indexing.sh.out b/go/reg-test/expected/case-positional-indexing.sh.out
deleted file mode 100644
index b76e18930..000000000
--- a/go/reg-test/expected/case-positional-indexing.sh.out
+++ /dev/null
@@ -1,70 +0,0 @@
-
-mlr --oxtab --from reg-test/input/abixy head -n 1 then put 
-  $_1 = ""; # just for visual output-spacing
-  $srec_keyed_by_2        = $[2];
-  $srec_name_2            = $[[2]];
-  $srec_value_2           = $[[[2]]];
-  $_2 = "";
-  $dollar_star_keyed_by_2 = $*[2];
-  $dollar_star_name_2     = $*[[2]];
-  $dollar_star_value_2    = $*[[[2]]];
-  $_3 = "";
-  mymap                   = {"a":7, "b":8, "c":9};
-  $mymap_keyed_by_2       = mymap[2];
-  $mymap_name_2           = mymap[[2]];
-  $mymap_value_2          = mymap[[[2]]];
-  $_4 = "";
-  myarray                 = [7, 8, 9];
-  $myarray_keyed_by_2     = myarray[2];
-  $myarray_name_2         = myarray[[2]];
-  $myarray_value_2        = myarray[[[2]]];
-
-a                   pan
-b                   pan
-i                   1
-x                   0.3467901443380824
-y                   0.7268028627434533
-_1                  
-srec_name_2         b
-srec_value_2        pan
-_2                  
-dollar_star_name_2  b
-dollar_star_value_2 pan
-_3                  
-mymap_name_2        b
-mymap_value_2       8
-_4                  
-myarray_keyed_by_2  8
-myarray_name_2      2
-myarray_value_2     8
-
-mlr --oxtab --from reg-test/input/abixy head -n 1 then put 
-  $_1 = ""; # just for visual output-spacing
-  $srec_keyed_by_2        = $[900];
-  $srec_name_2            = $[[900]];
-  $srec_value_2           = $[[[900]]];
-  $_2 = "";
-  $dollar_star_keyed_by_2 = $*[900];
-  $dollar_star_name_2     = $*[[900]];
-  $dollar_star_value_2    = $*[[[900]]];
-  $_3 = "";
-  mymap                   = {"a":7, "b":8, "c":9};
-  $mymap_keyed_by_2       = mymap[900];
-  $mymap_name_2           = mymap[[900]];
-  $mymap_value_2          = mymap[[[900]]];
-  $_4 = "";
-  myarray                 = [7, 8, 9];
-  $myarray_keyed_by_2     = myarray[900];
-  $myarray_name_2         = myarray[[900]];
-  $myarray_value_2        = myarray[[[900]]];
-
-a  pan
-b  pan
-i  1
-x  0.3467901443380824
-y  0.7268028627434533
-_1 
-_2 
-_3 
-_4 
-
diff --git a/go/src/miller/dsl/cst/lvalues.go b/go/src/miller/dsl/cst/lvalues.go
index 312c1992d..e0497af95 100644
--- a/go/src/miller/dsl/cst/lvalues.go
+++ b/go/src/miller/dsl/cst/lvalues.go
@@ -52,14 +52,15 @@ func (this *RootNode) BuildAssignableNode(
 		return this.BuildLocalVariableLvalueNode(astNode)
 		break
 
-	case dsl.NodeTypeArrayOrMapIndexAccess:
-		return this.BuildIndexedLvalueNode(astNode)
-		break
 	case dsl.NodeTypeArrayOrMapPositionalNameAccess:
-		return nil, nil // TODO
+		return this.BuildArrayOrMapPositionalNameAccessLvalueNode(astNode)
 		break
 	case dsl.NodeTypeArrayOrMapPositionalValueAccess:
-		return nil, nil // TODO
+		return this.BuildArrayOrMapPositionalValueAccessLvalueNode(astNode)
+		break
+
+	case dsl.NodeTypeArrayOrMapIndexAccess:
+		return this.BuildIndexedLvalueNode(astNode)
 		break
 
 	case dsl.NodeTypeEnvironmentVariable:
@@ -773,6 +774,195 @@ func (this *LocalVariableLvalueNode) UnsetIndexed(
 	}
 }
 
+// ----------------------------------------------------------------
+// Set the name at 2nd positional index in the current stream record: e.g.
+// '$[[2]] = "abc"
+
+type ArrayOrMapPositionalNameAccessLvalueNode struct {
+	lhsFieldIndexExpression IEvaluable
+}
+
+func (this *RootNode) BuildArrayOrMapPositionalNameAccessLvalueNode(
+	astNode *dsl.ASTNode,
+) (IAssignable, error) {
+	lib.InternalCodingErrorIf(astNode.Type != dsl.NodeTypeArrayOrMapPositionalNameAccess)
+	lib.InternalCodingErrorIf(astNode == nil)
+	lib.InternalCodingErrorIf(len(astNode.Children) != 1)
+	lhsFieldIndexExpression, err := this.BuildEvaluableNode(astNode.Children[0])
+	if err != nil {
+		return nil, err
+	}
+
+	return NewArrayOrMapPositionalNameAccessLvalueNode(lhsFieldIndexExpression), nil
+}
+
+func NewArrayOrMapPositionalNameAccessLvalueNode(
+	lhsFieldIndexExpression IEvaluable,
+) *ArrayOrMapPositionalNameAccessLvalueNode {
+	return &ArrayOrMapPositionalNameAccessLvalueNode{
+		lhsFieldIndexExpression: lhsFieldIndexExpression,
+	}
+}
+
+func (this *ArrayOrMapPositionalNameAccessLvalueNode) Assign(
+	rvalue *types.Mlrval,
+	state *State,
+) error {
+	// AssignmentNode checks for absentness of the rvalue, so we just assign
+	// whatever we get
+	lib.InternalCodingErrorIf(rvalue.IsAbsent())
+
+	lhsFieldIndex := this.lhsFieldIndexExpression.Evaluate(state)
+
+	index, ok := lhsFieldIndex.GetIntValue()
+	if ok {
+		// TODO: incorporate error-return into this API
+		state.Inrec.PutNameWithPositionalIndex(index, rvalue)
+		return nil
+	} else {
+		return errors.New(
+			fmt.Sprintf(
+				"Miller: positional index for $[[...]] assignment must be integer; got %s.",
+				lhsFieldIndex.GetTypeName(),
+			),
+		)
+	}
+}
+
+func (this *ArrayOrMapPositionalNameAccessLvalueNode) AssignIndexed(
+	rvalue *types.Mlrval,
+	indices []*types.Mlrval,
+	state *State,
+) error {
+	// TODO: reconsider this if /when we decide to allow string-slice
+	// assignments.
+	return errors.New(
+		"Miller: $[[...]] = ... expressions are not indexable.",
+	)
+}
+
+func (this *ArrayOrMapPositionalNameAccessLvalueNode) Unset(
+	state *State,
+) {
+	this.UnsetIndexed(nil, state)
+}
+
+func (this *ArrayOrMapPositionalNameAccessLvalueNode) UnsetIndexed(
+	indices []*types.Mlrval,
+	state *State,
+) {
+	lhsFieldIndex := this.lhsFieldIndexExpression.Evaluate(state)
+	if indices == nil {
+		name := lhsFieldIndex.String()
+		// xxx positional
+		state.Inrec.Remove(&name)
+	} else {
+		// xxx positional
+		state.Inrec.UnsetIndexed(
+			append([]*types.Mlrval{&lhsFieldIndex}, indices...),
+		)
+	}
+}
+
+// ----------------------------------------------------------------
+// Set the value at 2nd positional index in the current stream record: e.g.
+// '$[[[2]]] = "abc"
+
+type ArrayOrMapPositionalValueAccessLvalueNode struct {
+	lhsFieldIndexExpression IEvaluable
+}
+
+func (this *RootNode) BuildArrayOrMapPositionalValueAccessLvalueNode(
+	astNode *dsl.ASTNode,
+) (IAssignable, error) {
+	lib.InternalCodingErrorIf(astNode.Type != dsl.NodeTypeArrayOrMapPositionalValueAccess)
+	lib.InternalCodingErrorIf(astNode == nil)
+	lib.InternalCodingErrorIf(len(astNode.Children) != 1)
+	lhsFieldIndexExpression, err := this.BuildEvaluableNode(astNode.Children[0])
+	if err != nil {
+		return nil, err
+	}
+
+	return NewArrayOrMapPositionalValueAccessLvalueNode(lhsFieldIndexExpression), nil
+}
+
+func NewArrayOrMapPositionalValueAccessLvalueNode(
+	lhsFieldIndexExpression IEvaluable,
+) *ArrayOrMapPositionalValueAccessLvalueNode {
+	return &ArrayOrMapPositionalValueAccessLvalueNode{
+		lhsFieldIndexExpression: lhsFieldIndexExpression,
+	}
+}
+
+func (this *ArrayOrMapPositionalValueAccessLvalueNode) Assign(
+	rvalue *types.Mlrval,
+	state *State,
+) error {
+	return this.AssignIndexed(rvalue, nil, state)
+}
+
+func (this *ArrayOrMapPositionalValueAccessLvalueNode) AssignIndexed(
+	rvalue *types.Mlrval,
+	indices []*types.Mlrval,
+	state *State,
+) error {
+	// AssignmentNode checks for absentness of the rvalue, so we just assign
+	// whatever we get
+	lib.InternalCodingErrorIf(rvalue.IsAbsent())
+
+	lhsFieldIndex := this.lhsFieldIndexExpression.Evaluate(state)
+
+	if indices == nil {
+		index, ok := lhsFieldIndex.GetIntValue()
+		if ok {
+			// TODO: incorporate error-return into this API
+			//err := state.Inrec.PutCopyWithPositionalIndex(&lhsFieldIndex, rvalue)
+			//if err != nil {
+			//return err
+			//}
+			//return nil
+			state.Inrec.PutCopyWithPositionalIndex(index, rvalue)
+			return nil
+		} else {
+			return errors.New(
+				fmt.Sprintf(
+					"Miller: positional index for $[[[...]]] assignment must be integer; got %s.",
+					lhsFieldIndex.GetTypeName(),
+				),
+			)
+		}
+	} else {
+		// xxx positional
+		return state.Inrec.PutIndexed(
+			append([]*types.Mlrval{&lhsFieldIndex}, indices...),
+			rvalue,
+		)
+	}
+}
+
+func (this *ArrayOrMapPositionalValueAccessLvalueNode) Unset(
+	state *State,
+) {
+	this.UnsetIndexed(nil, state)
+}
+
+func (this *ArrayOrMapPositionalValueAccessLvalueNode) UnsetIndexed(
+	indices []*types.Mlrval,
+	state *State,
+) {
+	lhsFieldIndex := this.lhsFieldIndexExpression.Evaluate(state)
+	if indices == nil {
+		name := lhsFieldIndex.String()
+		// xxx positional
+		state.Inrec.Remove(&name)
+	} else {
+		// xxx positional
+		state.Inrec.UnsetIndexed(
+			append([]*types.Mlrval{&lhsFieldIndex}, indices...),
+		)
+	}
+}
+
 // ----------------------------------------------------------------
 // IndexedValueNode is a delegator to base-lvalue types.
 // * The baseLvalue is some IAssignable