diff --git a/c/containers/mlrval.c b/c/containers/mlrval.c
index f76a63c10..cd78cec45 100644
--- a/c/containers/mlrval.c
+++ b/c/containers/mlrval.c
@@ -1757,6 +1757,18 @@ mv_t b_x_isnotnull_func(mv_t* pval1) {
 	return rv;
 }
 
+// ----------------------------------------------------------------
+mv_t b_x_isabsent_func(mv_t* pval1) {
+	mv_t rv = mv_from_bool(mv_is_absent(pval1));
+	mv_free(pval1);
+	return rv;
+}
+mv_t b_x_ispresent_func(mv_t* pval1) {
+	mv_t rv = mv_from_bool(mv_is_present(pval1));
+	mv_free(pval1);
+	return rv;
+}
+
 // ----------------------------------------------------------------
 static mv_t boolean_v_x(mv_t* pa) { return mv_void(); }
 static mv_t boolean_e_x(mv_t* pa) { return mv_error(); }
diff --git a/c/containers/mlrval.h b/c/containers/mlrval.h
index 5ee52b210..671d68c4f 100644
--- a/c/containers/mlrval.h
+++ b/c/containers/mlrval.h
@@ -213,6 +213,12 @@ static inline int mv_is_null_or_error(mv_t* pval) {
 static inline int mv_is_non_null(mv_t* pval) {
 	return MT_ERROR < pval->type && pval->type > MT_VOID;
 }
+static inline int mv_is_absent(mv_t* pval) {
+	return pval->type == MT_ABSENT;
+}
+static inline int mv_is_present(mv_t* pval) {
+	return pval->type != MT_ABSENT;
+}
 
 // ----------------------------------------------------------------
 // AUXILIARY METHODS
@@ -320,6 +326,8 @@ mv_t x_xx_roundm_func(mv_t* pval1, mv_t* pval2);
 
 mv_t b_x_isnull_func(mv_t* pval1);
 mv_t b_x_isnotnull_func(mv_t* pval1);
+mv_t b_x_isabsent_func(mv_t* pval1);
+mv_t b_x_ispresent_func(mv_t* pval1);
 mv_t i_x_int_func(mv_t* pval1);
 mv_t f_x_float_func(mv_t* pval1);
 mv_t b_x_boolean_func(mv_t* pval1);
diff --git a/c/mapping/rval_func_evaluators.c b/c/mapping/rval_func_evaluators.c
index 8d26d5469..bca1b2570 100644
--- a/c/mapping/rval_func_evaluators.c
+++ b/c/mapping/rval_func_evaluators.c
@@ -61,6 +61,8 @@ function_lookup_t FUNCTION_LOOKUP_TABLE[] = {
 
 	{FUNC_CLASS_CONVERSION, "isnull",    1, "True if argument is null, false otherwise"},
 	{FUNC_CLASS_CONVERSION, "isnotnull", 1, "False if argument is null, true otherwise."},
+	{FUNC_CLASS_CONVERSION, "isabsent",    1, "False if field is present in input, false otherwise"},
+	{FUNC_CLASS_CONVERSION, "ispresent", 1, "True if field is present in input, false otherwise."},
 	{FUNC_CLASS_CONVERSION, "boolean",   1, "Convert int/float/bool/string to boolean."},
 	{FUNC_CLASS_CONVERSION, "float",     1, "Convert int/float/bool/string to float."},
 	{FUNC_CLASS_CONVERSION, "fmtnum",    2,
@@ -335,8 +337,10 @@ rval_evaluator_t* rval_evaluator_alloc_from_unary_func_name(char* fnnm, rval_eva
 	} else if (streq(fnnm, "hms2sec"))   { return rval_evaluator_alloc_from_f_s_func(i_s_hms2sec_func,   parg1);
 	} else if (streq(fnnm, "int"))       { return rval_evaluator_alloc_from_x_x_func(i_x_int_func,       parg1);
 	} else if (streq(fnnm, "invqnorm"))  { return rval_evaluator_alloc_from_f_f_func(f_f_invqnorm_func,  parg1);
+	} else if (streq(fnnm, "isabsent"))  { return rval_evaluator_alloc_from_x_x_func(b_x_isabsent_func,  parg1);
 	} else if (streq(fnnm, "isnotnull")) { return rval_evaluator_alloc_from_x_x_func(b_x_isnotnull_func, parg1);
 	} else if (streq(fnnm, "isnull"))    { return rval_evaluator_alloc_from_x_x_func(b_x_isnull_func,    parg1);
+	} else if (streq(fnnm, "ispresent")) { return rval_evaluator_alloc_from_x_x_func(b_x_ispresent_func, parg1);
 	} else if (streq(fnnm, "log"))       { return rval_evaluator_alloc_from_f_f_func(f_f_log_func,       parg1);
 	} else if (streq(fnnm, "log10"))     { return rval_evaluator_alloc_from_f_f_func(f_f_log10_func,     parg1);
 	} else if (streq(fnnm, "log1p"))     { return rval_evaluator_alloc_from_f_f_func(f_f_log1p_func,     parg1);
@@ -351,11 +355,11 @@ rval_evaluator_t* rval_evaluator_alloc_from_unary_func_name(char* fnnm, rval_eva
 	} else if (streq(fnnm, "sqrt"))      { return rval_evaluator_alloc_from_f_f_func(f_f_sqrt_func,      parg1);
 	} else if (streq(fnnm, "string"))    { return rval_evaluator_alloc_from_x_x_func(s_x_string_func,    parg1);
 	} else if (streq(fnnm, "strlen"))    { return rval_evaluator_alloc_from_i_s_func(i_s_strlen_func,    parg1);
-	} else if (streq(fnnm, "typeof"))    { return rval_evaluator_alloc_from_x_x_func(s_x_typeof_func,    parg1);
 	} else if (streq(fnnm, "tan"))       { return rval_evaluator_alloc_from_f_f_func(f_f_tan_func,       parg1);
 	} else if (streq(fnnm, "tanh"))      { return rval_evaluator_alloc_from_f_f_func(f_f_tanh_func,      parg1);
 	} else if (streq(fnnm, "tolower"))   { return rval_evaluator_alloc_from_s_s_func(s_s_tolower_func,   parg1);
 	} else if (streq(fnnm, "toupper"))   { return rval_evaluator_alloc_from_s_s_func(s_s_toupper_func,   parg1);
+	} else if (streq(fnnm, "typeof"))    { return rval_evaluator_alloc_from_x_x_func(s_x_typeof_func,    parg1);
 
 	} else return NULL;
 }
diff --git a/c/output/out-dev b/c/output/out-dev
index e1b462325..8cc679cae 100644
--- a/c/output/out-dev
+++ b/c/output/out-dev
@@ -3,653 +3,6 @@
 OLD NULL-HANDLING
 
 
----------------------------------------------------------------- ok
-mlr put $z = $x + $y ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,z=3
-x=1,y=,s=,z=
-x=,y=,s=hurrah,z=
-
-
----------------------------------------------------------------- ok
-mlr put $z = $y + $y ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,z=4
-x=1,y=,s=,z=
-x=,y=,s=hurrah,z=
-
-
----------------------------------------------------------------- FIXME FOR SRECS
-mlr put $z = $x + $nosuch ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,z=1
-x=1,y=,s=,z=1
-x=,y=,s=hurrah,z=
-
-
----------------------------------------------------------------- ok
-mlr put $t = sub($s,       "ell", "X") ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,t=hXo
-x=1,y=,s=,t=
-x=,y=,s=hurrah,t=hurrah
-
-
----------------------------------------------------------------- ok
-mlr put $t = sub($s,       "ell", "") ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,t=ho
-x=1,y=,s=,t=
-x=,y=,s=hurrah,t=hurrah
-
-
----------------------------------------------------------------- ok
-mlr put $t = sub($nosuch,  "ell", "X") ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,t=
-x=1,y=,s=,t=
-x=,y=,s=hurrah,t=
-
-
----------------------------------------------------------------- ok
-mlr put $t = gsub($s,      "l",   "X") ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,t=heXXo
-x=1,y=,s=,t=
-x=,y=,s=hurrah,t=hurrah
-
-
----------------------------------------------------------------- ok
-mlr put $t = gsub($s,      "l",   "") ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,t=heo
-x=1,y=,s=,t=
-x=,y=,s=hurrah,t=hurrah
-
-
----------------------------------------------------------------- ok
-mlr put $t = gsub($nosuch, "l",   "X") ./reg_test/input/null-vs-empty.dkvp
-x=1,y=2,s=hello,t=
-x=1,y=,s=,t=
-x=,y=,s=hurrah,t=
-
-
-================================================================
-NULLITY PREDICATES
-
-mlr --opprint filter isnull($x) ./reg_test/input/nullvals.dkvp
-a x y z
-b - 6 -
-b - - -
-
-mlr --opprint filter isnull($y) ./reg_test/input/nullvals.dkvp
-a x y z
-b 5 - -
-b - - -
-
-mlr --opprint filter isnull($z) ./reg_test/input/nullvals.dkvp
-a x y z
-b 1 2 -
-b 3 4 -
-b 5 - -
-b - 6 -
-b - - -
-
-mlr --opprint filter isnull($nosuch) ./reg_test/input/nullvals.dkvp
-a x y z
-b 1 2 -
-b 3 4 -
-b 5 - -
-b - 6 -
-b - - -
-
-mlr --opprint filter isnotnull($x) ./reg_test/input/nullvals.dkvp
-a x y z
-b 1 2 -
-b 3 4 -
-b 5 - -
-
-mlr --opprint filter isnotnull($y) ./reg_test/input/nullvals.dkvp
-a x y z
-b 1 2 -
-b 3 4 -
-b - 6 -
-
-mlr --opprint filter isnotnull($z) ./reg_test/input/nullvals.dkvp
-
-mlr --opprint filter isnotnull($nosuch) ./reg_test/input/nullvals.dkvp
-
-mlr --opprint put $f=isnull($x) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - false
-b 3 4 - false
-b 5 - - false
-b - 6 - true
-b - - - true
-
-mlr --opprint put $f=isnull($y) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - false
-b 3 4 - false
-b 5 - - true
-b - 6 - false
-b - - - true
-
-mlr --opprint put $f=isnull($z) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - true
-b 3 4 - true
-b 5 - - true
-b - 6 - true
-b - - - true
-
-mlr --opprint put $f=isnull($nosuch) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - true
-b 3 4 - true
-b 5 - - true
-b - 6 - true
-b - - - true
-
-mlr --opprint put $f=isnotnull($x) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - true
-b 3 4 - true
-b 5 - - true
-b - 6 - false
-b - - - false
-
-mlr --opprint put $f=isnotnull($y) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - true
-b 3 4 - true
-b 5 - - false
-b - 6 - true
-b - - - false
-
-mlr --opprint put $f=isnotnull($z) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - false
-b 3 4 - false
-b 5 - - false
-b - 6 - false
-b - - - false
-
-mlr --opprint put $f=isnotnull($nosuch) ./reg_test/input/nullvals.dkvp
-a x y z f
-b 1 2 - false
-b 3 4 - false
-b 5 - - false
-b - 6 - false
-b - - - false
-
-
-================================================================
-TRI-SPLIT-NULL HANDLING
-
-
----------------------------------------------------------------- ok
-mlr put -q @sum     += $x; end{emitp @sum} ./reg_test/input/abixy
-sum=4.536294
-
-
----------------------------------------------------------------- ok
-mlr put -q @sum[$a] += $x; end{emitp @sum, "a"} ./reg_test/input/abixy
-a=pan,sum=0.849416
-a=eks,sum=1.751863
-a=wye,sum=0.777892
-a=zee,sum=1.125680
-a=hat,sum=0.031442
-
-
----------------------------------------------------------------- ok
-mlr put $nonesuch = @nonesuch ./reg_test/input/abixy
-a=pan,b=pan,i=1,x=0.3467901443380824,y=0.7268028627434533,nonesuch=
-a=eks,b=pan,i=2,x=0.7586799647899636,y=0.5221511083334797,nonesuch=
-a=wye,b=wye,i=3,x=0.20460330576630303,y=0.33831852551664776,nonesuch=
-a=eks,b=wye,i=4,x=0.38139939387114097,y=0.13418874328430463,nonesuch=
-a=wye,b=pan,i=5,x=0.5732889198020006,y=0.8636244699032729,nonesuch=
-a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697,nonesuch=
-a=eks,b=zee,i=7,x=0.6117840605678454,y=0.1878849191181694,nonesuch=
-a=zee,b=wye,i=8,x=0.5985540091064224,y=0.976181385699006,nonesuch=
-a=hat,b=wye,i=9,x=0.03144187646093577,y=0.7495507603507059,nonesuch=
-a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864,nonesuch=
-
-
----------------------------------------------------------------- ok
-mlr put -q @sum     += $x; end{emitp @sum} ./reg_test/input/abixy-het
-sum=3.963005
-
-
----------------------------------------------------------------- ok
-mlr put -q @sum[$a] += $x; end{emitp @sum, "a"} ./reg_test/input/abixy-het
-a=pan,sum=0.849416
-a=eks,sum=1.751863
-a=wye,sum=
-a=zee,sum=1.125680
-
-
----------------------------------------------------------------- ok
-mlr put $nonesuch = @nonesuch ./reg_test/input/abixy-het
-a=pan,b=pan,i=1,x=0.3467901443380824,y=0.7268028627434533,nonesuch=
-a=eks,b=pan,i=2,x=0.7586799647899636,y=0.5221511083334797,nonesuch=
-aaa=wye,b=wye,i=3,x=0.20460330576630303,y=0.33831852551664776,nonesuch=
-a=eks,bbb=wye,i=4,x=0.38139939387114097,y=0.13418874328430463,nonesuch=
-a=wye,b=pan,i=5,xxx=0.5732889198020006,y=0.8636244699032729,nonesuch=
-a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697,nonesuch=
-a=eks,b=zee,iii=7,x=0.6117840605678454,y=0.1878849191181694,nonesuch=
-a=zee,b=wye,i=8,x=0.5985540091064224,yyy=0.976181385699006,nonesuch=
-aaa=hat,bbb=wye,i=9,x=0.03144187646093577,y=0.7495507603507059,nonesuch=
-a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864,nonesuch=
-
-mlr put -q @sum += $x; @sumtype = typeof(@sum); @xtype = typeof($x); emitf @sumtype, @xtype, @sum; end{emitp @sum} ./reg_test/input/abixy
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=0.346790
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=1.105470
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=1.310073
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=1.691473
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=2.264762
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=2.791888
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=3.403672
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=4.002226
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=4.033668
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=4.536294
-sum=4.536294
-
-mlr put -q @sum += $x; @sumtype = typeof(@sum); @xtype = typeof($x); emitf @sumtype, @xtype, @sum; end{emitp @sum} ./reg_test/input/abixy-het
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=0.346790
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=1.105470
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=1.310073
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=1.691473
-sumtype=MT_FLOAT,xtype=MT_ABSENT,sum=1.691473
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=2.218599
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=2.830383
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=3.428937
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=3.460379
-sumtype=MT_FLOAT,xtype=MT_FLOAT,sum=3.963005
-sum=3.963005
-
-mlr put $z = $x + $y ./reg_test/input/typeof.dkvp
-x=1,y=2,z=3
-x=1,y=,z=
-x=,y=2,z=
-x=,y=,z=
-
-mlr put $z = $x + $y ./reg_test/input/typeof.dkvp
-x=1,y=2,z=3
-x=1,y=,z=
-x=,y=2,z=
-x=,y=,z=
-
-mlr put $z = $x + $u ./reg_test/input/typeof.dkvp
-x=1,y=2,z=1
-x=1,y=,z=1
-x=,y=2,z=
-x=,y=,z=
-
-mlr put @s = @s + $y; emitp @s ./reg_test/input/typeof.dkvp
-s=2
-x=1,y=2
-s=
-x=1,y=
-s=
-x=,y=2
-s=
-x=,y=
-
-mlr put @s = @s + $y; emitp @s ./reg_test/input/typeof.dkvp
-s=2
-x=1,y=2
-s=
-x=1,y=
-s=
-x=,y=2
-s=
-x=,y=
-
-mlr put @s = @s + $u; emitp @s ./reg_test/input/typeof.dkvp
-s=
-x=1,y=2
-s=
-x=1,y=
-s=
-x=,y=2
-s=
-x=,y=
-
-mlr put $z = $x + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z) ./reg_test/input/typeof.dkvp
-x=MT_INT,y=MT_INT,z=MT_INT
-x=MT_INT,y=MT_VOID,z=MT_VOID
-x=MT_VOID,y=MT_INT,z=MT_VOID
-x=MT_VOID,y=MT_VOID,z=MT_VOID
-
-mlr put $z = $x + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z) ./reg_test/input/typeof.dkvp
-x=MT_INT,y=MT_INT,z=MT_INT
-x=MT_INT,y=MT_VOID,z=MT_VOID
-x=MT_VOID,y=MT_INT,z=MT_VOID
-x=MT_VOID,y=MT_VOID,z=MT_VOID
-
-mlr put $z = $x + $u; $x=typeof($x);$y=typeof($y);$z=typeof($z) ./reg_test/input/typeof.dkvp
-x=MT_INT,y=MT_INT,z=MT_INT
-x=MT_INT,y=MT_VOID,z=MT_INT
-x=MT_VOID,y=MT_INT,z=MT_VOID
-x=MT_VOID,y=MT_VOID,z=MT_VOID
-
-mlr put @s = @s + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s) ./reg_test/input/typeof.dkvp
-x=MT_INT,y=MT_INT,z=MT_ABSENT,s=MT_INT
-x=MT_INT,y=MT_VOID,z=MT_ABSENT,s=MT_VOID
-x=MT_VOID,y=MT_INT,z=MT_ABSENT,s=MT_VOID
-x=MT_VOID,y=MT_VOID,z=MT_ABSENT,s=MT_VOID
-
-mlr put @s = @s + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s) ./reg_test/input/typeof.dkvp
-x=MT_INT,y=MT_INT,z=MT_ABSENT,s=MT_INT
-x=MT_INT,y=MT_VOID,z=MT_ABSENT,s=MT_VOID
-x=MT_VOID,y=MT_INT,z=MT_ABSENT,s=MT_VOID
-x=MT_VOID,y=MT_VOID,z=MT_ABSENT,s=MT_VOID
-
-mlr put @s = @s + $u; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s) ./reg_test/input/typeof.dkvp
-x=MT_INT,y=MT_INT,z=MT_ABSENT,s=MT_VOID
-x=MT_INT,y=MT_VOID,z=MT_ABSENT,s=MT_VOID
-x=MT_VOID,y=MT_INT,z=MT_ABSENT,s=MT_VOID
-x=MT_VOID,y=MT_VOID,z=MT_ABSENT,s=MT_VOID
-
-
-================================================================
-ABSENT-HANDLING
-
-
----------------------------------------------------------------- FIXME FOR SRECS
-mlr put $a = $a * 2 ./reg_test/input/absent.dkvp
-a=2,b=2
-a=,b=4
-x=,b=6,a=2
-a=14,b=8
-
-
----------------------------------------------------------------- FIXME FOR SRECS
-mlr put $new = $a * 2 ./reg_test/input/absent.dkvp
-a=1,b=2,new=2
-a=,b=4,new=
-x=,b=6,new=2
-a=7,b=8,new=14
-
-
----------------------------------------------------------------- ok for oosvars
-mlr put $new = @nonesuch * 2 ./reg_test/input/absent.dkvp
-a=1,b=2,new=2
-a=,b=4,new=2
-x=,b=6,new=2
-a=7,b=8,new=2
-
-
----------------------------------------------------------------- ok
-mlr put begin {@somesuch = 10 }; $new = @somesuch * 2 ./reg_test/input/absent.dkvp
-a=1,b=2,new=20
-a=,b=4,new=20
-x=,b=6,new=20
-a=7,b=8,new=20
-
-
----------------------------------------------------------------- FIXME FOR SRECS
-mlr put $new = @nonesuch * $a ./reg_test/input/absent.dkvp
-a=1,b=2,new=1
-a=,b=4,new=
-x=,b=6,new=
-a=7,b=8,new=7
-
-
----------------------------------------------------------------- ok
-mlr put begin {@somesuch = 10 }; $new = @somesuch * $a ./reg_test/input/absent.dkvp
-a=1,b=2,new=10
-a=,b=4,new=
-x=,b=6,new=10
-a=7,b=8,new=70
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put @sum = @sum + $a; emit @sum; end { emit @sum } ./reg_test/input/absent.dkvp
-sum=1
-a=1,b=2
-sum=
-a=,b=4
-sum=
-x=,b=6
-sum=
-a=7,b=8
-sum=
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put @product = @product * $a; emit @product; end { emit @product } ./reg_test/input/absent.dkvp
-product=1
-a=1,b=2
-product=
-a=,b=4
-product=
-x=,b=6
-product=
-a=7,b=8
-product=
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put begin { @sum = 10 }; @sum = @sum + $a; emit @sum; end { emit @sum } ./reg_test/input/absent.dkvp
-sum=11
-a=1,b=2
-sum=
-a=,b=4
-sum=
-x=,b=6
-sum=
-a=7,b=8
-sum=
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put begin { @product = 10 }; @product = @product * $a; emit @product; end { emit @product } ./reg_test/input/absent.dkvp
-product=10
-a=1,b=2
-product=
-a=,b=4
-product=
-x=,b=6
-product=
-a=7,b=8
-product=
-
-
-================================================================
-COMPARE OLD TESTS TO NEW
-
-
----------------------------------------------------------------- raw input
-mlr cat ./reg_test/input/abixy-het
-a=pan,b=pan,i=1,x=0.3467901443380824,y=0.7268028627434533
-a=eks,b=pan,i=2,x=0.7586799647899636,y=0.5221511083334797
-aaa=wye,b=wye,i=3,x=0.20460330576630303,y=0.33831852551664776
-a=eks,bbb=wye,i=4,x=0.38139939387114097,y=0.13418874328430463
-a=wye,b=pan,i=5,xxx=0.5732889198020006,y=0.8636244699032729
-a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697
-a=eks,b=zee,iii=7,x=0.6117840605678454,y=0.1878849191181694
-a=zee,b=wye,i=8,x=0.5985540091064224,yyy=0.976181385699006
-aaa=hat,bbb=wye,i=9,x=0.03144187646093577,y=0.7495507603507059
-a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864
-
-
----------------------------------------------------------------- ok
-mlr put -q @sum     += $x; end{emitp @sum} ./reg_test/input/abixy-het
-sum=3.963005
-
-
----------------------------------------------------------------- ok
-mlr put -q @sum[$a] += $x; end{emitp @sum, "a"} ./reg_test/input/abixy-het
-a=pan,sum=0.849416
-a=eks,sum=1.751863
-a=wye,sum=
-a=zee,sum=1.125680
-
-
----------------------------------------------------------------- ok
-mlr put $nonesuch = @nonesuch ./reg_test/input/abixy-het
-a=pan,b=pan,i=1,x=0.3467901443380824,y=0.7268028627434533,nonesuch=
-a=eks,b=pan,i=2,x=0.7586799647899636,y=0.5221511083334797,nonesuch=
-aaa=wye,b=wye,i=3,x=0.20460330576630303,y=0.33831852551664776,nonesuch=
-a=eks,bbb=wye,i=4,x=0.38139939387114097,y=0.13418874328430463,nonesuch=
-a=wye,b=pan,i=5,xxx=0.5732889198020006,y=0.8636244699032729,nonesuch=
-a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697,nonesuch=
-a=eks,b=zee,iii=7,x=0.6117840605678454,y=0.1878849191181694,nonesuch=
-a=zee,b=wye,i=8,x=0.5985540091064224,yyy=0.976181385699006,nonesuch=
-aaa=hat,bbb=wye,i=9,x=0.03144187646093577,y=0.7495507603507059,nonesuch=
-a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864,nonesuch=
-
-
----------------------------------------------------------------- raw input
-mlr cat ./reg_test/input/absent.dkvp
-a=1,b=2
-a=,b=4
-x=,b=6
-a=7,b=8
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put @sum = @sum + $a; emit @sum; end { emit @sum } ./reg_test/input/absent.dkvp
-sum=1
-a=1,b=2
-sum=
-a=,b=4
-sum=
-x=,b=6
-sum=
-a=7,b=8
-sum=
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put @product = @product * $a; emit @product; end { emit @product } ./reg_test/input/absent.dkvp
-product=1
-a=1,b=2
-product=
-a=,b=4
-product=
-x=,b=6
-product=
-a=7,b=8
-product=
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put begin { @sum = 10 }; @sum = @sum + $a; emit @sum; end { emit @sum } ./reg_test/input/absent.dkvp
-sum=11
-a=1,b=2
-sum=
-a=,b=4
-sum=
-x=,b=6
-sum=
-a=7,b=8
-sum=
-
-
----------------------------------------------------------------- FIXME AND COMPARE TO ABOVE
-mlr put begin { @product = 10 }; @product = @product * $a; emit @product; end { emit @product } ./reg_test/input/absent.dkvp
-product=10
-a=1,b=2
-product=
-a=,b=4
-product=
-x=,b=6
-product=
-a=7,b=8
-product=
-
-
----------------------------------------------------------------- COMPARE
-mlr put emit @sum; @sum += $x; emit @sum; end { emit @sum } ./reg_test/input/abixy-het
-sum=0.346790
-a=pan,b=pan,i=1,x=0.3467901443380824,y=0.7268028627434533
-sum=0.346790
-sum=1.105470
-a=eks,b=pan,i=2,x=0.7586799647899636,y=0.5221511083334797
-sum=1.105470
-sum=1.310073
-aaa=wye,b=wye,i=3,x=0.20460330576630303,y=0.33831852551664776
-sum=1.310073
-sum=1.691473
-a=eks,bbb=wye,i=4,x=0.38139939387114097,y=0.13418874328430463
-sum=1.691473
-sum=1.691473
-a=wye,b=pan,i=5,xxx=0.5732889198020006,y=0.8636244699032729
-sum=1.691473
-sum=2.218599
-a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697
-sum=2.218599
-sum=2.830383
-a=eks,b=zee,iii=7,x=0.6117840605678454,y=0.1878849191181694
-sum=2.830383
-sum=3.428937
-a=zee,b=wye,i=8,x=0.5985540091064224,yyy=0.976181385699006
-sum=3.428937
-sum=3.460379
-aaa=hat,bbb=wye,i=9,x=0.03144187646093577,y=0.7495507603507059
-sum=3.460379
-sum=3.963005
-a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864
-sum=3.963005
-
-
----------------------------------------------------------------- COMPARE
-mlr put emit @sum; @sum += $a; emit @sum; end { emit @sum } ./reg_test/input/absent.dkvp
-sum=1
-a=1,b=2
-sum=1
-sum=
-a=,b=4
-sum=
-sum=
-x=,b=6
-sum=
-sum=
-a=7,b=8
-sum=
-
-mlr put emit @sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum += $x; $nstype=typeof(@sum);emit @sum; end { emit @sum } ./reg_test/input/abixy-het
-sum=0.346790
-a=pan,b=pan,i=1,x=0.3467901443380824,y=0.7268028627434533,ostype=MT_UNINIT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=0.346790
-sum=1.105470
-a=eks,b=pan,i=2,x=0.7586799647899636,y=0.5221511083334797,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=1.105470
-sum=1.310073
-aaa=wye,b=wye,i=3,x=0.20460330576630303,y=0.33831852551664776,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=1.310073
-sum=1.691473
-a=eks,bbb=wye,i=4,x=0.38139939387114097,y=0.13418874328430463,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=1.691473
-sum=1.691473
-a=wye,b=pan,i=5,xxx=0.5732889198020006,y=0.8636244699032729,ostype=MT_FLOAT,xtype=MT_ABSENT,nstype=MT_FLOAT
-sum=1.691473
-sum=2.218599
-a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=2.218599
-sum=2.830383
-a=eks,b=zee,iii=7,x=0.6117840605678454,y=0.1878849191181694,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=2.830383
-sum=3.428937
-a=zee,b=wye,i=8,x=0.5985540091064224,yyy=0.976181385699006,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=3.428937
-sum=3.460379
-aaa=hat,bbb=wye,i=9,x=0.03144187646093577,y=0.7495507603507059,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=3.460379
-sum=3.963005
-a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864,ostype=MT_FLOAT,xtype=MT_FLOAT,nstype=MT_FLOAT
-sum=3.963005
-
-mlr put emit @sum; $ostype=typeof(@sum);$atype=typeof($a);@sum += $a; $nstype=typeof(@sum);emit @sum; end { emit @sum } ./reg_test/input/absent.dkvp
-sum=1
-a=1,b=2,ostype=MT_UNINIT,atype=MT_INT,nstype=MT_INT
-sum=1
-sum=
-a=,b=4,ostype=MT_INT,atype=MT_VOID,nstype=MT_VOID
-sum=
-sum=
-x=,b=6,ostype=MT_VOID,atype=MT_ABSENT,nstype=MT_VOID
-sum=
-sum=
-a=7,b=8,ostype=MT_VOID,atype=MT_INT,nstype=MT_VOID
-sum=
-
-
 ================================================================
 NARROW IN
 
@@ -660,10 +13,16 @@ x=1
 x=
 x=7
 
-mlr put $osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum += $x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }
-x=1,osum=,ostype=MT_UNINIT,xtype=MT_INT,nstype=MT_INT,nsum=1
-x=,osum=1,ostype=MT_INT,xtype=MT_VOID,nstype=MT_VOID,nsum=
-x=7,osum=,ostype=MT_VOID,xtype=MT_INT,nstype=MT_VOID,nsum=
+mlr --ofs tab put $osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum+=$x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }
+x=1	osum=	ostype=MT_UNINIT	xtype=MT_INT	nstype=MT_INT	nsum=1
+x=	osum=1	ostype=MT_INT	xtype=MT_VOID	nstype=MT_VOID	nsum=
+x=7	osum=	ostype=MT_VOID	xtype=MT_INT	nstype=MT_VOID	nsum=
+sum=
+
+mlr --ofs tab put $osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);ispresent($x){@sum+=$x}; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }
+x=1	osum=	ostype=MT_UNINIT	xtype=MT_INT	nstype=MT_INT	nsum=1
+x=	osum=1	ostype=MT_INT	xtype=MT_VOID	nstype=MT_VOID	nsum=
+x=7	osum=	ostype=MT_VOID	xtype=MT_INT	nstype=MT_VOID	nsum=
 sum=
 
 
@@ -673,10 +32,16 @@ x=1
 xxx=
 x=7
 
-mlr put $osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum += $x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }
-x=1,osum=,ostype=MT_UNINIT,xtype=MT_INT,nstype=MT_INT,nsum=1
-xxx=,osum=1,ostype=MT_INT,xtype=MT_ABSENT,nstype=MT_INT,nsum=1
-x=7,osum=1,ostype=MT_INT,xtype=MT_INT,nstype=MT_INT,nsum=8
+mlr --ofs tab put $osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum+=$x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }
+x=1	osum=	ostype=MT_UNINIT	xtype=MT_INT	nstype=MT_INT	nsum=1
+xxx=	osum=1	ostype=MT_INT	xtype=MT_ABSENT	nstype=MT_ABSENT	nsum=
+x=7	osum=	ostype=MT_ABSENT	xtype=MT_INT	nstype=MT_ABSENT	nsum=
+sum=
+
+mlr --ofs tab put $osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);ispresent($x){@sum+=$x}; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }
+x=1	osum=	ostype=MT_UNINIT	xtype=MT_INT	nstype=MT_INT	nsum=1
+xxx=	osum=1	ostype=MT_INT	xtype=MT_ABSENT	nstype=MT_INT	nsum=1
+x=7	osum=1	ostype=MT_INT	xtype=MT_INT	nstype=MT_INT	nsum=8
 sum=8
 
 
@@ -690,6 +55,12 @@ x=7
 mlr --ofs tab put $xtype=typeof($x);$sum = $x + 10; $stype=typeof($sum)
 x=1	xtype=MT_INT	sum=11	stype=MT_INT
 x=	xtype=MT_VOID	sum=	stype=MT_VOID
-y=	xtype=MT_ABSENT	sum=10	stype=MT_INT
+y=	xtype=MT_ABSENT	sum=	stype=MT_ABSENT
+x=7	xtype=MT_INT	sum=17	stype=MT_INT
+
+mlr --ofs tab put $xtype=typeof($x);$sum = ispresent($x) ? $x + 10 : 999; $stype=typeof($sum)
+x=1	xtype=MT_INT	sum=11	stype=MT_INT
+x=	xtype=MT_VOID	sum=	stype=MT_VOID
+y=	xtype=MT_ABSENT	sum=999	stype=MT_INT
 x=7	xtype=MT_INT	sum=17	stype=MT_INT
 
diff --git a/c/reg_test/dev b/c/reg_test/dev
index 04e2c4ec2..670d61056 100755
--- a/c/reg_test/dev
+++ b/c/reg_test/dev
@@ -76,152 +76,6 @@ run_mlr() {
 # ================================================================
 announce OLD NULL-HANDLING
 
-mention ok
-run_mlr put '$z = $x + $y'      $indir/null-vs-empty.dkvp
-mention ok
-run_mlr put '$z = $y + $y'      $indir/null-vs-empty.dkvp
-mention FIXME FOR SRECS
-run_mlr put '$z = $x + $nosuch' $indir/null-vs-empty.dkvp
-
-mention ok
-run_mlr put '$t = sub($s,       "ell", "X")' $indir/null-vs-empty.dkvp
-mention ok
-run_mlr put '$t = sub($s,       "ell", "")'  $indir/null-vs-empty.dkvp
-mention ok
-run_mlr put '$t = sub($nosuch,  "ell", "X")' $indir/null-vs-empty.dkvp
-mention ok
-run_mlr put '$t = gsub($s,      "l",   "X")' $indir/null-vs-empty.dkvp
-mention ok
-run_mlr put '$t = gsub($s,      "l",   "")'  $indir/null-vs-empty.dkvp
-mention ok
-run_mlr put '$t = gsub($nosuch, "l",   "X")' $indir/null-vs-empty.dkvp
-
-# ================================================================
-announce NULLITY PREDICATES
-
-run_mlr --opprint filter 'isnull($x)'         $indir/nullvals.dkvp
-run_mlr --opprint filter 'isnull($y)'         $indir/nullvals.dkvp
-run_mlr --opprint filter 'isnull($z)'         $indir/nullvals.dkvp
-run_mlr --opprint filter 'isnull($nosuch)'    $indir/nullvals.dkvp
-run_mlr --opprint filter 'isnotnull($x)'      $indir/nullvals.dkvp
-run_mlr --opprint filter 'isnotnull($y)'      $indir/nullvals.dkvp
-run_mlr --opprint filter 'isnotnull($z)'      $indir/nullvals.dkvp
-run_mlr --opprint filter 'isnotnull($nosuch)' $indir/nullvals.dkvp
-
-run_mlr --opprint put '$f=isnull($x)'         $indir/nullvals.dkvp
-run_mlr --opprint put '$f=isnull($y)'         $indir/nullvals.dkvp
-run_mlr --opprint put '$f=isnull($z)'         $indir/nullvals.dkvp
-run_mlr --opprint put '$f=isnull($nosuch)'    $indir/nullvals.dkvp
-run_mlr --opprint put '$f=isnotnull($x)'      $indir/nullvals.dkvp
-run_mlr --opprint put '$f=isnotnull($y)'      $indir/nullvals.dkvp
-run_mlr --opprint put '$f=isnotnull($z)'      $indir/nullvals.dkvp
-run_mlr --opprint put '$f=isnotnull($nosuch)' $indir/nullvals.dkvp
-
-# ================================================================
-announce TRI-SPLIT-NULL HANDLING
-
-mention ok
-run_mlr put -q '@sum     += $x; end{emitp @sum}'      $indir/abixy
-mention ok
-run_mlr put -q '@sum[$a] += $x; end{emitp @sum, "a"}' $indir/abixy
-mention ok
-run_mlr put    '$nonesuch = @nonesuch' $indir/abixy
-
-mention ok
-run_mlr put -q '@sum     += $x; end{emitp @sum}'      $indir/abixy-het
-mention ok
-run_mlr put -q '@sum[$a] += $x; end{emitp @sum, "a"}' $indir/abixy-het
-mention ok
-run_mlr put    '$nonesuch = @nonesuch' $indir/abixy-het
-
-run_mlr put -q '@sum += $x; @sumtype = typeof(@sum); @xtype = typeof($x); emitf @sumtype, @xtype, @sum; end{emitp @sum}' $indir/abixy
-run_mlr put -q '@sum += $x; @sumtype = typeof(@sum); @xtype = typeof($x); emitf @sumtype, @xtype, @sum; end{emitp @sum}' $indir/abixy-het
-
-run_mlr put '$z = $x + $y' $indir/typeof.dkvp
-run_mlr put '$z = $x + $y' $indir/typeof.dkvp
-run_mlr put '$z = $x + $u' $indir/typeof.dkvp
-
-run_mlr put '@s = @s + $y; emitp @s' $indir/typeof.dkvp
-run_mlr put '@s = @s + $y; emitp @s' $indir/typeof.dkvp
-run_mlr put '@s = @s + $u; emitp @s' $indir/typeof.dkvp
-
-run_mlr put '$z = $x + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z)' $indir/typeof.dkvp
-run_mlr put '$z = $x + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z)' $indir/typeof.dkvp
-run_mlr put '$z = $x + $u; $x=typeof($x);$y=typeof($y);$z=typeof($z)' $indir/typeof.dkvp
-
-run_mlr put '@s = @s + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s)' $indir/typeof.dkvp
-run_mlr put '@s = @s + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s)' $indir/typeof.dkvp
-run_mlr put '@s = @s + $u; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s)' $indir/typeof.dkvp
-
-# ================================================================
-announce ABSENT-HANDLING
-
-mention FIXME FOR SRECS
-run_mlr put '$a = $a * 2' $indir/absent.dkvp
-
-mention FIXME FOR SRECS
-run_mlr put '$new = $a * 2' $indir/absent.dkvp
-
-mention ok for oosvars
-run_mlr put '$new = @nonesuch * 2' $indir/absent.dkvp
-
-mention ok
-run_mlr put 'begin {@somesuch = 10 }; $new = @somesuch * 2' $indir/absent.dkvp
-
-mention FIXME FOR SRECS
-run_mlr put '$new = @nonesuch * $a' $indir/absent.dkvp
-
-mention ok
-run_mlr put 'begin {@somesuch = 10 }; $new = @somesuch * $a' $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put '@sum = @sum + $a; emit @sum; end { emit @sum }' $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put '@product = @product * $a; emit @product; end { emit @product }' $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put 'begin { @sum = 10 }; @sum = @sum + $a; emit @sum; end { emit @sum }' $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put 'begin { @product = 10 }; @product = @product * $a; emit @product; end { emit @product }' $indir/absent.dkvp
-
-# ================================================================
-announce COMPARE OLD TESTS TO NEW
-
-mention raw input
-run_mlr cat $indir/abixy-het
-mention ok
-run_mlr put -q '@sum     += $x; end{emitp @sum}'      $indir/abixy-het
-mention ok
-run_mlr put -q '@sum[$a] += $x; end{emitp @sum, "a"}' $indir/abixy-het
-mention ok
-run_mlr put    '$nonesuch = @nonesuch' $indir/abixy-het
-
-mention raw input
-run_mlr cat $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put '@sum = @sum + $a; emit @sum; end { emit @sum }' $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put '@product = @product * $a; emit @product; end { emit @product }' $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put 'begin { @sum = 10 }; @sum = @sum + $a; emit @sum; end { emit @sum }' $indir/absent.dkvp
-
-mention FIXME AND COMPARE TO ABOVE
-run_mlr put 'begin { @product = 10 }; @product = @product * $a; emit @product; end { emit @product }' $indir/absent.dkvp
-
-mention COMPARE
-run_mlr put 'emit @sum; @sum += $x; emit @sum; end { emit @sum }' $indir/abixy-het
-
-mention COMPARE
-run_mlr put 'emit @sum; @sum += $a; emit @sum; end { emit @sum }' $indir/absent.dkvp
-
-run_mlr put 'emit @sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum += $x; $nstype=typeof(@sum);emit @sum; end { emit @sum }' $indir/abixy-het|redden xxx
-run_mlr put 'emit @sum; $ostype=typeof(@sum);$atype=typeof($a);@sum += $a; $nstype=typeof(@sum);emit @sum; end { emit @sum }' $indir/absent.dkvp
-
 # ================================================================
 announce NARROW IN
 
@@ -232,7 +86,13 @@ x=
 x=7
 EOF
 
-run_mlr put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum += $x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum+=$x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+x=1
+x=
+x=7
+EOF
+
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);ispresent($x){@sum+=$x}; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
 x=1
 x=
 x=7
@@ -245,7 +105,13 @@ xxx=
 x=7
 EOF
 
-run_mlr put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum += $x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum+=$x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+x=1
+xxx=
+x=7
+EOF
+
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);ispresent($x){@sum+=$x}; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
 x=1
 xxx=
 x=7
@@ -266,6 +132,13 @@ y=
 x=7
 EOF
 
+run_mlr --ofs tab put '$xtype=typeof($x);$sum = ispresent($x) ? $x + 10 : 999; $stype=typeof($sum)' <<EOF
+x=1
+x=
+y=
+x=7
+EOF
+
 # ================================================================
 cat $outfile
 
diff --git a/c/reg_test/run b/c/reg_test/run
index 67cb7ba99..a915f30c6 100755
--- a/c/reg_test/run
+++ b/c/reg_test/run
@@ -1335,6 +1335,64 @@ run_mlr put '@s = @s + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@
 run_mlr put '@s = @s + $y; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s)' $indir/typeof.dkvp
 run_mlr put '@s = @s + $u; $x=typeof($x);$y=typeof($y);$z=typeof($z);$s=typeof(@s)' $indir/typeof.dkvp
 
+run_mlr cat << EOF
+x=1
+x=
+x=7
+EOF
+
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum+=$x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+x=1
+x=
+x=7
+EOF
+
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);ispresent($x){@sum+=$x}; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+x=1
+x=
+x=7
+EOF
+
+run_mlr cat << EOF
+x=1
+xxx=
+x=7
+EOF
+
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);@sum+=$x; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+x=1
+xxx=
+x=7
+EOF
+
+run_mlr --ofs tab put '$osum=@sum; $ostype=typeof(@sum);$xtype=typeof($x);ispresent($x){@sum+=$x}; $nstype=typeof(@sum);$nsum=@sum; end { emit @sum }' <<EOF
+x=1
+xxx=
+x=7
+EOF
+
+run_mlr cat << EOF
+x=1
+x=
+y=
+x=7
+EOF
+
+run_mlr --ofs tab put '$xtype=typeof($x);$sum = $x + 10; $stype=typeof($sum)' <<EOF
+x=1
+x=
+y=
+x=7
+EOF
+
+run_mlr --ofs tab put '$xtype=typeof($x);$sum = ispresent($x) ? $x + 10 : 999; $stype=typeof($sum)' <<EOF
+x=1
+x=
+y=
+x=7
+EOF
+
+
 # ----------------------------------------------------------------
 announce PARAMETERIZED EMIT