Fix #814: raise on div-0, add inf isinf nan isnan

8 files changed, 477 insertions, 388 deletions

diff --git a/builtin.c b/builtin.c
index 745c9c51..8fb04622 100644
--- a/builtin.c
+++ b/builtin.c
@@ -216,6 +216,8 @@ static jv f_multiply(jq_state *jq, jv input, jv a, jv b) {
 static jv f_divide(jq_state *jq, jv input, jv a, jv b) {
   jv_free(input);
   if (jv_get_kind(a) == JV_KIND_NUMBER && jv_get_kind(b) == JV_KIND_NUMBER) {
+    if (jv_number_value(b) == 0.0)
+      return type_error2(a, b, "cannot be divided because the divisor is zero");
     return jv_number(jv_number_value(a) / jv_number_value(b));
   } else if (jv_get_kind(a) == JV_KIND_STRING && jv_get_kind(b) == JV_KIND_STRING) {
     return jv_string_split(a, b);
@@ -227,12 +229,11 @@ static jv f_divide(jq_state *jq, jv input, jv a, jv b) {
 static jv f_mod(jq_state *jq, jv input, jv a, jv b) {
   jv_free(input);
   if (jv_get_kind(a) == JV_KIND_NUMBER && jv_get_kind(b) == JV_KIND_NUMBER) {
-    if ((intmax_t)jv_number_value(b) == 0) {
-      return jv_invalid_with_msg(jv_string("Cannot mod by zero."));
-    }
+    if ((intmax_t)jv_number_value(b) == 0)
+      return type_error2(a, b, "cannot be divided (remainder) because the divisor is zero");
     return jv_number((intmax_t)jv_number_value(a) % (intmax_t)jv_number_value(b));
   } else {
-    return type_error2(a, b, "cannot be divided");
+    return type_error2(a, b, "cannot be divided (remainder)");
   }  
 }
 
@@ -831,6 +832,38 @@ static jv f_type(jq_state *jq, jv input) {
   return out;
 }
 
+static jv f_isinf(jq_state *jq, jv input) {
+  jv_kind k = jv_get_kind(input);
+  if (k != JV_KIND_NUMBER) {
+    jv_free(input);
+    return jv_false();
+  }
+  double n = jv_number_value(input);
+  jv_free(input);
+  return isinf(n) ? jv_true() : jv_false();
+}
+
+static jv f_isnan(jq_state *jq, jv input) {
+  jv_kind k = jv_get_kind(input);
+  if (k != JV_KIND_NUMBER) {
+    jv_free(input);
+    return jv_false();
+  }
+  double n = jv_number_value(input);
+  jv_free(input);
+  return isnan(n) ? jv_true() : jv_false();
+}
+
+static jv f_inf(jq_state *jq, jv input) {
+  jv_free(input);
+  return jv_number(INFINITY);
+}
+
+static jv f_nan(jq_state *jq, jv input) {
+  jv_free(input);
+  return jv_number(NAN);
+}
+
 static jv f_error(jq_state *jq, jv input, jv msg) {
   jv_free(input);
   return jv_invalid_with_msg(msg);
@@ -1183,6 +1216,10 @@ static const struct cfunction function_list[] = {
   {(cfunction_ptr)f_contains, "contains", 2},
   {(cfunction_ptr)f_length, "length", 1},
   {(cfunction_ptr)f_type, "type", 1},
+  {(cfunction_ptr)f_isinf, "isinf", 1},
+  {(cfunction_ptr)f_isnan, "isnan", 1},
+  {(cfunction_ptr)f_inf, "inf", 1},
+  {(cfunction_ptr)f_nan, "nan", 1},
   {(cfunction_ptr)f_sort, "sort", 1},
   {(cfunction_ptr)f_sort_by_impl, "_sort_by_impl", 2},
   {(cfunction_ptr)f_group_by_impl, "_group_by_impl", 2},
diff --git a/compile.c b/compile.c
index 02653ac7..742d1f54 100644
--- a/compile.c
+++ b/compile.c
@@ -2,6 +2,7 @@
 #define _GNU_SOURCE // for strdup
 #endif
 #include <assert.h>
+#include <math.h>
 #include <string.h>
 #include <stdlib.h>
 #include "compile.h"
@@ -161,6 +162,12 @@ int block_is_const(block b) {
   return (block_is_single(b) && b.first->op == LOADK);
 }
 
+int block_is_const_inf(block b) {
+  return (block_is_single(b) && b.first->op == LOADK &&
+          jv_get_kind(b.first->imm.constant) == JV_KIND_NUMBER &&
+          isinf(jv_number_value(b.first->imm.constant)));
+}
+
 jv_kind block_const_kind(block b) {
   assert(block_is_const(b));
   return jv_get_kind(b.first->imm.constant);
diff --git a/compile.h b/compile.h
index b3a28230..2ef193ef 100644
--- a/compile.h
+++ b/compile.h
@@ -22,6 +22,7 @@ block gen_op_simple(opcode op);
 block gen_const(jv constant);
 block gen_const_global(jv constant, const char *name);
 int block_is_const(block b);
+int block_is_const_inf(block b);
 jv_kind block_const_kind(block b);
 jv block_const(block b);
 block gen_op_target(opcode op, block target);
diff --git a/docs/content/3.manual/manual.yml b/docs/content/3.manual/manual.yml
index 8a4f77a1..8a3e20aa 100644
--- a/docs/content/3.manual/manual.yml
+++ b/docs/content/3.manual/manual.yml
@@ -598,7 +598,7 @@ sections:
           that string that many times.
 
           Dividing a string by another splits the first using the second
-          as separators.
+          as separators.  Division by zero raises an error.
 
           Multiplying two objects will merge them recursively: this works
           like addition but if both objects contain a value for the
@@ -615,6 +615,9 @@ sections:
           - program: '{"k": {"a": 1, "b": 2}} * {"k": {"a": 0,"c": 3}}'
             input: 'null'
             output: ['{"k": {"a": 0, "b": 2, "c": 3}}']
+          - program: '.[] | (1 / .)?'
+            input: '[1,0,-1]'
+            output: ['1', '-1']
 
 
       - title: "`length`"
@@ -1073,6 +1076,25 @@ sections:
             input: '[0, false, [], {}, null, "hello"]'
             output: ['["number", "boolean", "array", "object", "null", "string"]']
 
+      - title: "`inf`, `nan`, `isinf`, `isnan`"
+        body: |
+
+          Some arithmetic operations can yield infinities and "not a
+          number" (NaN) values.  The `isinf` builtin returns `true` if
+          its input is infinite.  The `isnan` builtin returns `true` if
+          its input is a NaN.  The `inf` builtin returns a positive
+          infinite value.  The `nan` builtin returns a NaN.
+
+          Note that division by zero raises an error.
+
+        examples:
+          - program: '.[] | (inf * .) < 0'
+            input: '[-1, 1]'
+            output: ['true', 'false']
+          - program: 'inf, nan | type'
+            input: 'null'
+            output: ['"number"']
+
       - title: "`sort, sort_by(path_expression)`"
         body: |
 
diff --git a/parser.c b/parser.c
index 63cbcb93..70ae4b3b 100644
--- a/parser.c
+++ b/parser.c
@@ -64,15 +64,16 @@
 /* Copy the first part of user declarations.  */
 #line 1 "parser.y" /* yacc.c:339  */
 
+#include <assert.h>
+#include <math.h>
 #include <stdio.h>
 #include <string.h>
-#include <assert.h>
 #include "compile.h"
 #include "jv_alloc.h"
 #define YYMALLOC jv_mem_alloc
 #define YYFREE jv_mem_free
 
-#line 76 "parser.c" /* yacc.c:339  */
+#line 77 "parser.c" /* yacc.c:339  */
 
 # ifndef YY_NULLPTR
 #  if defined __cplusplus && 201103L <= __cplusplus
@@ -102,7 +103,7 @@
 extern int yydebug;
 #endif
 /* "%code requires" blocks.  */
-#line 10 "parser.y" /* yacc.c:355  */
+#line 11 "parser.y" /* yacc.c:355  */
 
 #include "locfile.h"
 struct lexer_param;
@@ -120,7 +121,7 @@ struct lexer_param;
   } while (0)
  
 
-#line 124 "parser.c" /* yacc.c:355  */
+#line 125 "parser.c" /* yacc.c:355  */
 
 /* Token type.  */
 #ifndef YYTOKENTYPE
@@ -218,12 +219,12 @@ struct lexer_param;
 typedef union YYSTYPE YYSTYPE;
 union YYSTYPE
 {
-#line 30 "parser.y" /* yacc.c:355  */
+#line 31 "parser.y" /* yacc.c:355  */
 
   jv literal;
   block blk;
 
-#line 227 "parser.c" /* yacc.c:355  */
+#line 228 "parser.c" /* yacc.c:355  */
 };
 # define YYSTYPE_IS_TRIVIAL 1
 # define YYSTYPE_IS_DECLARED 1
@@ -250,7 +251,7 @@ int yyparse (block* answer, int* errors, struct locfile* locations, struct lexer
 #endif /* !YY_YY_PARSER_H_INCLUDED  */
 
 /* Copy the second part of user declarations.  */
-#line 112 "parser.y" /* yacc.c:358  */
+#line 113 "parser.y" /* yacc.c:358  */
 
 #include "lexer.h"
 struct lexer_param {
@@ -406,7 +407,7 @@ static block gen_update(block object, block val, int optype) {
 }
 
 
-#line 410 "parser.c" /* yacc.c:358  */
+#line 411 "parser.c" /* yacc.c:358  */
 
 #ifdef short
 # undef short
@@ -709,22 +710,22 @@ static const yytype_uint8 yytranslate[] =
   /* YYRLINE[YYN] -- Source line where rule number YYN was defined.  */
 static const yytype_uint16 yyrline[] =
 {
-       0,   270,   270,   273,   278,   281,   291,   294,   299,   302,
-     307,   311,   315,   319,   323,   327,   330,   335,   339,   343,
-     348,   360,   364,   368,   372,   376,   380,   384,   388,   392,
-     396,   400,   404,   408,   412,   416,   420,   424,   428,   432,
-     436,   440,   444,   448,   452,   456,   460,   464,   469,   478,
-     485,   497,   511,   516,   522,   525,   530,   535,   542,   542,
-     546,   546,   553,   556,   559,   565,   568,   573,   576,   579,
-     585,   588,   591,   599,   603,   606,   609,   612,   615,   618,
-     621,   624,   627,   631,   637,   640,   643,   646,   649,   652,
-     655,   658,   661,   664,   667,   670,   673,   676,   679,   682,
-     685,   692,   696,   700,   712,   717,   718,   719,   720,   723,
-     726,   731,   736,   740,   743,   748,   751,   756,   759,   764,
-     767,   770,   773,   778,   781,   784,   787,   790,   793,   796,
-     799,   802,   805,   808,   811,   814,   817,   820,   823,   826,
-     829,   834,   837,   838,   839,   842,   845,   848,   851,   855,
-     859,   862
+       0,   271,   271,   274,   279,   282,   292,   295,   300,   303,
+     308,   312,   316,   320,   324,   328,   331,   336,   340,   344,
+     349,   361,   365,   369,   373,   377,   381,   385,   389,   393,
+     397,   401,   405,   409,   413,   417,   421,   425,   431,   437,
+     441,   445,   449,   453,   457,   461,   465,   469,   474,   483,
+     490,   502,   516,   521,   527,   530,   535,   540,   547,   547,
+     551,   551,   558,   561,   564,   570,   573,   578,   581,   584,
+     590,   593,   596,   604,   608,   611,   614,   617,   620,   623,
+     626,   629,   632,   636,   642,   645,   648,   651,   654,   657,
+     660,   663,   666,   669,   672,   675,   678,   681,   684,   687,
+     690,   697,   701,   705,   717,   722,   723,   724,   725,   728,
+     731,   736,   741,   745,   748,   753,   756,   761,   764,   769,
+     772,   775,   778,   783,   786,   789,   792,   795,   798,   801,
+     804,   807,   810,   813,   816,   819,   822,   825,   828,   831,
+     834,   839,   842,   843,   844,   847,   850,   853,   856,   860,
+     864,   867
 };
 #endif
 
@@ -1849,165 +1850,165 @@ yydestruct (const char *yymsg, int yytype, YYSTYPE *yyvaluep, YYLTYPE *yylocatio
   switch (yytype)
     {
           case 4: /* IDENT  */
-#line 35 "parser.y" /* yacc.c:1257  */
+#line 36 "parser.y" /* yacc.c:1257  */
       { jv_free(((*yyvaluep).literal)); }
-#line 1855 "parser.c" /* yacc.c:1257  */
+#line 1856 "parser.c" /* yacc.c:1257  */
         break;
 
     case 5: /* FIELD  */
-#line 35 "parser.y" /* yacc.c:1257  */
+#line 36 "parser.y" /* yacc.c:1257  */
       { jv_free(((*yyvaluep).literal)); }
-#line 1861 "parser.c" /* yacc.c:1257  */
+#line 1862 "parser.c" /* yacc.c:1257  */
         break;
 
     case 6: /* LITERAL  */
-#line 35 "parser.y" /* yacc.c:1257  */
+#line 36 "parser.y" /* yacc.c:1257  */
       { jv_free(((*yyvaluep).literal)); }
-#line 1867 "parser.c" /* yacc.c:1257  */
+#line 1868 "parser.c" /* yacc.c:1257  */
         break;
 
     case 7: /* FORMAT  */
-#line 35 "parser.y" /* yacc.c:1257  */
+#line 36 "parser.y" /* yacc.c:1257  */
       { jv_free(((*yyvaluep).literal)); }
-#line 1873 "parser.c" /* yacc.c:1257  */
+#line 1874 "parser.c" /* yacc.c:1257  */
         break;
 
     case 40: /* QQSTRING_TEXT  */
-#line 35 "parser.y" /* yacc.c:1257  */
+#line 36 "parser.y" /* yacc.c:1257  */
       { jv_free(((*yyvaluep).literal)); }
-#line 1879 "parser.c" /* yacc.c:1257  */
+#line 1880 "parser.c" /* yacc.c:1257  */
         break;
 
     case 67: /* Module  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1885 "parser.c" /* yacc.c:1257  */
+#line 1886 "parser.c" /* yacc.c:1257  */
         break;
 
     case 68: /* Imports  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1891 "parser.c" /* yacc.c:1257  */
+#line 1892 "parser.c" /* yacc.c:1257  */
         break;
 
     case 69: /* FuncDefs  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1897 "parser.c" /* yacc.c:1257  */
+#line 1898 "parser.c" /* yacc.c:1257  */
         break;
 
     case 70: /* Exp  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1903 "parser.c" /* yacc.c:1257  */
+#line 1904 "parser.c" /* yacc.c:1257  */
         break;
 
     case 71: /* Import  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1909 "parser.c" /* yacc.c:1257  */
+#line 1910 "parser.c" /* yacc.c:1257  */
         break;
 
     case 72: /* FuncDef  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1915 "parser.c" /* yacc.c:1257  */
+#line 1916 "parser.c" /* yacc.c:1257  */
         break;
 
     case 73: /* Params  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1921 "parser.c" /* yacc.c:1257  */
+#line 1922 "parser.c" /* yacc.c:1257  */
         break;
 
     case 74: /* Param  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1927 "parser.c" /* yacc.c:1257  */
+#line 1928 "parser.c" /* yacc.c:1257  */
         break;
 
     case 75: /* String  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1933 "parser.c" /* yacc.c:1257  */
+#line 1934 "parser.c" /* yacc.c:1257  */
         break;
 
     case 78: /* QQString  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1939 "parser.c" /* yacc.c:1257  */
+#line 1940 "parser.c" /* yacc.c:1257  */
         break;
 
     case 79: /* ElseBody  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1945 "parser.c" /* yacc.c:1257  */
+#line 1946 "parser.c" /* yacc.c:1257  */
         break;
 
     case 80: /* ExpD  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1951 "parser.c" /* yacc.c:1257  */
+#line 1952 "parser.c" /* yacc.c:1257  */
         break;
 
     case 81: /* Term  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1957 "parser.c" /* yacc.c:1257  */
+#line 1958 "parser.c" /* yacc.c:1257  */
         break;
 
     case 82: /* Args  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1963 "parser.c" /* yacc.c:1257  */
+#line 1964 "parser.c" /* yacc.c:1257  */
         break;
 
     case 83: /* Arg  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1969 "parser.c" /* yacc.c:1257  */
+#line 1970 "parser.c" /* yacc.c:1257  */
         break;
 
     case 84: /* Pattern  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1975 "parser.c" /* yacc.c:1257  */
+#line 1976 "parser.c" /* yacc.c:1257  */
         break;
 
     case 85: /* ArrayPats  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1981 "parser.c" /* yacc.c:1257  */
+#line 1982 "parser.c" /* yacc.c:1257  */
         break;
 
     case 86: /* ObjPats  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1987 "parser.c" /* yacc.c:1257  */
+#line 1988 "parser.c" /* yacc.c:1257  */
         break;
 
     case 87: /* ObjPat  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 1993 "parser.c" /* yacc.c:1257  */
+#line 1994 "parser.c" /* yacc.c:1257  */
         break;
 
     case 88: /* Keyword  */
-#line 35 "parser.y" /* yacc.c:1257  */
+#line 36 "parser.y" /* yacc.c:1257  */
       { jv_free(((*yyvaluep).literal)); }
-#line 1999 "parser.c" /* yacc.c:1257  */
+#line 2000 "parser.c" /* yacc.c:1257  */
         break;
 
     case 89: /* MkDict  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 2005 "parser.c" /* yacc.c:1257  */
+#line 2006 "parser.c" /* yacc.c:1257  */
         break;
 
     case 90: /* MkDictPair  */
-#line 36 "parser.y" /* yacc.c:1257  */
+#line 37 "parser.y" /* yacc.c:1257  */
       { block_free(((*yyvaluep).blk)); }
-#line 2011 "parser.c" /* yacc.c:1257  */
+#line 2012 "parser.c" /* yacc.c:1257  */
         break;
 
 
@@ -2299,31 +2300,31 @@ yyreduce:
   switch (yyn)
     {
         case 2:
-#line 270 "parser.y" /* yacc.c:1646  */
+#line 271 "parser.y" /* yacc.c:1646  */
     {
   *answer = BLOCK((yyvsp[-2].blk), (yyvsp[-1].blk), gen_op_simple(TOP), (yyvsp[0].blk));
 }
-#line 2307 "parser.c" /* yacc.c:1646  */
+#line 2308 "parser.c" /* yacc.c:1646  */
     break;
 
   case 3:
-#line 273 "parser.y" /* yacc.c:1646  */
+#line 274 "parser.y" /* yacc.c:1646  */
     {
   *answer = BLOCK((yyvsp[-2].blk), (yyvsp[-1].blk), (yyvsp[0].blk));
 }
-#line 2315 "parser.c" /* yacc.c:1646  */
+#line 2316 "parser.c" /* yacc.c:1646  */
     break;
 
   case 4:
-#line 278 "parser.y" /* yacc.c:1646  */
+#line 279 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_noop();
 }
-#line 2323 "parser.c" /* yacc.c:1646  */
+#line 2324 "parser.c" /* yacc.c:1646  */
     break;
 
   case 5:
-#line 281 "parser.y" /* yacc.c:1646  */
+#line 282 "parser.y" /* yacc.c:1646  */
     {
   if (!block_is_const((yyvsp[-1].blk))) {
     FAIL((yyloc), "Module metadata must be constant.");
@@ -2332,354 +2333,358 @@ yyreduce:
     (yyval.blk) = gen_module((yyvsp[-1].blk));
   }
 }
-#line 2336 "parser.c" /* yacc.c:1646  */
+#line 2337 "parser.c" /* yacc.c:1646  */
     break;
 
   case 6:
-#line 291 "parser.y" /* yacc.c:1646  */
+#line 292 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_noop();
 }
-#line 2344 "parser.c" /* yacc.c:1646  */
+#line 2345 "parser.c" /* yacc.c:1646  */
     break;
 
   case 7:
-#line 294 "parser.y" /* yacc.c:1646  */
+#line 295 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = BLOCK((yyvsp[-1].blk), (yyvsp[0].blk));
 }
-#line 2352 "parser.c" /* yacc.c:1646  */
+#line 2353 "parser.c" /* yacc.c:1646  */
     break;
 
   case 8:
-#line 299 "parser.y" /* yacc.c:1646  */
+#line 300 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_noop();
 }
-#line 2360 "parser.c" /* yacc.c:1646  */
+#line 2361 "parser.c" /* yacc.c:1646  */
     break;
 
   case 9:
-#line 302 "parser.y" /* yacc.c:1646  */
+#line 303 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = block_bind((yyvsp[-1].blk), (yyvsp[0].blk), OP_IS_CALL_PSEUDO);
 }
-#line 2368 "parser.c" /* yacc.c:1646  */
+#line 2369 "parser.c" /* yacc.c:1646  */
     break;
 
   case 10:
-#line 307 "parser.y" /* yacc.c:1646  */
+#line 308 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = block_bind_referenced((yyvsp[-1].blk), (yyvsp[0].blk), OP_IS_CALL_PSEUDO);
 }
-#line 2376 "parser.c" /* yacc.c:1646  */
+#line 2377 "parser.c" /* yacc.c:1646  */
     break;
 
   case 11:
-#line 311 "parser.y" /* yacc.c:1646  */
+#line 312 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_destructure((yyvsp[-4].blk), (yyvsp[-2].blk), (yyvsp[0].blk));
 }
-#line 2384 "parser.c" /* yacc.c:1646  */
+#line 2385 "parser.c" /* yacc.c:1646  */
     break;
 
   case 12:
-#line 315 "parser.y" /* yacc.c:1646  */
+#line 316 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_reduce((yyvsp[-7].blk), (yyvsp[-5].blk), (yyvsp[-3].blk), (yyvsp[-1].blk));
 }
-#line 2392 "parser.c" /* yacc.c:1646  */
+#line 2393 "parser.c" /* yacc.c:1646  */
     break;
 
   case 13:
-#line 319 "parser.y" /* yacc.c:1646  */
+#line 320 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_foreach((yyvsp[-9].blk), (yyvsp[-7].blk), (yyvsp[-5].blk), (yyvsp[-3].blk), (yyvsp[-1].blk));
 }
-#line 2400 "parser.c" /* yacc.c:1646  */
+#line 2401 "parser.c" /* yacc.c:1646  */
     break;
 
   case 14:
-#line 323 "parser.y" /* yacc.c:1646  */
+#line 324 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_foreach((yyvsp[-7].blk), (yyvsp[-5].blk), (yyvsp[-3].blk), (yyvsp[-1].blk), gen_noop());
 }
-#line 2408 "parser.c" /* yacc.c:1646  */
+#line 2409 "parser.c" /* yacc.c:1646  */
     break;
 
   case 15:
-#line 327 "parser.y" /* yacc.c:1646  */
+#line 328 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_cond((yyvsp[-3].blk), (yyvsp[-1].blk), (yyvsp[0].blk));
 }
-#line 2416 "parser.c" /* yacc.c:1646  */
+#line 2417 "parser.c" /* yacc.c:1646  */
     break;
 
   case 16:
-#line 330 "parser.y" /* yacc.c:1646  */
+#line 331 "parser.y" /* yacc.c:1646  */
     {
   FAIL((yyloc), "Possibly unterminated 'if' statement");
   (yyval.blk) = (yyvsp[-2].blk);
 }
-#line 2425 "parser.c" /* yacc.c:1646  */
+#line 2426 "parser.c" /* yacc.c:1646  */
     break;
 
   case 17:
-#line 335 "parser.y" /* yacc.c:1646  */
+#line 336 "parser.y" /* yacc.c:1646  */
     {
   //$$ = BLOCK(gen_op_target(FORK_OPT, $2), $2, $4);
   (yyval.blk) = gen_try((yyvsp[-2].blk), gen_try_handler((yyvsp[0].blk)));
 }
-#line 2434 "parser.c" /* yacc.c:1646  */
+#line 2435 "parser.c" /* yacc.c:1646  */
     break;
 
   case 18:
-#line 339 "parser.y" /* yacc.c:1646  */
+#line 340 "parser.y" /* yacc.c:1646  */
     {
   //$$ = BLOCK(gen_op_target(FORK_OPT, $2), $2, gen_op_simple(BACKTRACK));
   (yyval.blk) = gen_try((yyvsp[0].blk), gen_op_simple(BACKTRACK));
 }
-#line 2443 "parser.c" /* yacc.c:1646  */
+#line 2444 "parser.c" /* yacc.c:1646  */
     break;
 
   case 19:
-#line 343 "parser.y" /* yacc.c:1646  */
+#line 344 "parser.y" /* yacc.c:1646  */
     {
   FAIL((yyloc), "Possibly unterminated 'try' statement");
   (yyval.blk) = (yyvsp[-2].blk);
 }
-#line 2452 "parser.c" /* yacc.c:1646  */
+#line 2453 "parser.c" /* yacc.c:1646  */
     break;
 
   case 20:
-#line 348 "parser.y" /* yacc.c:1646  */
+#line 349 "parser.y" /* yacc.c:1646  */
     {
   jv v = jv_string_fmt("*label-%s", jv_string_value((yyvsp[-2].literal)));
   (yyval.blk) = gen_location((yyloc), locations, gen_label(jv_string_value(v), (yyvsp[0].blk)));
   jv_free((yyvsp[-2].literal));
   jv_free(v);
 }
-#line 2463 "parser.c" /* yacc.c:1646  */
+#line 2464 "parser.c" /* yacc.c:1646  */
     break;
 
   case 21:
-#line 360 "parser.y" /* yacc.c:1646  */
+#line 361 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_try((yyvsp[-1].blk), gen_op_simple(BACKTRACK));
 }
-#line 2471 "parser.c" /* yacc.c:1646  */
+#line 2472 "parser.c" /* yacc.c:1646  */
     break;
 
   case 22:
-#line 364 "parser.y" /* yacc.c:1646  */
+#line 365 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_call("_assign", BLOCK(gen_lambda((yyvsp[-2].blk)), gen_lambda((yyvsp[0].blk))));
 }
-#line 2479 "parser.c" /* yacc.c:1646  */
+#line 2480 "parser.c" /* yacc.c:1646  */
     break;
 
   case 23:
-#line 368 "parser.y" /* yacc.c:1646  */
+#line 369 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_or((yyvsp[-2].blk), (yyvsp[0].blk));
 }
-#line 2487 "parser.c" /* yacc.c:1646  */
+#line 2488 "parser.c" /* yacc.c:1646  */
     break;
 
   case 24:
-#line 372 "parser.y" /* yacc.c:1646  */
+#line 373 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_and((yyvsp[-2].blk), (yyvsp[0].blk));
 }
-#line 2495 "parser.c" /* yacc.c:1646  */
+#line 2496 "parser.c" /* yacc.c:1646  */
     break;
 
   case 25:
-#line 376 "parser.y" /* yacc.c:1646  */
+#line 377 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_definedor((yyvsp[-2].blk), (yyvsp[0].blk));
 }
-#line 2503 "parser.c" /* yacc.c:1646  */
+#line 2504 "parser.c" /* yacc.c:1646  */
     break;
 
   case 26:
-#line 380 "parser.y" /* yacc.c:1646  */
+#line 381 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_definedor_assign((yyvsp[-2].blk), (yyvsp[0].blk));
 }
-#line 2511 "parser.c" /* yacc.c:1646  */
+#line 2512 "parser.c" /* yacc.c:1646  */
     break;
 
   case 27:
-#line 384 "parser.y" /* yacc.c:1646  */
+#line 385 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_call("_modify", BLOCK(gen_lambda((yyvsp[-2].blk)), gen_lambda((yyvsp[0].blk))));
 }
-#line 2519 "parser.c" /* yacc.c:1646  */
+#line 2520 "parser.c" /* yacc.c:1646  */
     break;
 
   case 28:
-#line 388 "parser.y" /* yacc.c:1646  */
+#line 389 "parser.y" /* yacc.c:1646  */
     { 
   (yyval.blk) = block_join((yyvsp[-2].blk), (yyvsp[0].blk)); 
 }
-#line 2527 "parser.c" /* yacc.c:1646  */
+#line 2528 "parser.c" /* yacc.c:1646  */
     break;
 
   case 29:
-#line 392 "parser.y" /* yacc.c:1646  */
+#line 393 "parser.y" /* yacc.c:1646  */
     { 
   (yyval.blk) = gen_both((yyvsp[-2].blk), (yyvsp[0].blk)); 
 }
-#line 2535 "parser.c" /* yacc.c:1646  */
+#line 2536 "parser.c" /* yacc.c:1646  */
     break;
 
   case 30:
-#line 396 "parser.y" /* yacc.c:1646  */
+#line 397 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), '+');
 }
-#line 2543 "parser.c" /* yacc.c:1646  */
+#line 2544 "parser.c" /* yacc.c:1646  */
     break;
 
   case 31:
-#line 400 "parser.y" /* yacc.c:1646  */
+#line 401 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_update((yyvsp[-2].blk), (yyvsp[0].blk), '+');
 }
-#line 2551 "parser.c" /* yacc.c:1646  */
+#line 2552 "parser.c" /* yacc.c:1646  */
     break;
 
   case 32:
-#line 404 "parser.y" /* yacc.c:1646  */
+#line 405 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = BLOCK((yyvsp[0].blk), gen_call("_negate", gen_noop()));
 }
-#line 2559 "parser.c" /* yacc.c:1646  */
+#line 2560 "parser.c" /* yacc.c:1646  */
     break;
 
   case 33:
-#line 408 "parser.y" /* yacc.c:1646  */
+#line 409 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), '-');
 }
-#line 2567 "parser.c" /* yacc.c:1646  */
+#line 2568 "parser.c" /* yacc.c:1646  */
     break;
 
   case 34:
-#line 412 "parser.y" /* yacc.c:1646  */
+#line 413 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_update((yyvsp[-2].blk), (yyvsp[0].blk), '-');
 }
-#line 2575 "parser.c" /* yacc.c:1646  */
+#line 2576 "parser.c" /* yacc.c:1646  */
     break;
 
   case 35:
-#line 416 "parser.y" /* yacc.c:1646  */
+#line 417 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), '*');
 }
-#line 2583 "parser.c" /* yacc.c:1646  */
+#line 2584 "parser.c" /* yacc.c:1646  */
     break;
 
   case 36:
-#line 420 "parser.y" /* yacc.c:1646  */
+#line 421 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_update((yyvsp[-2].blk), (yyvsp[0].blk), '*');
 }
-#line 2591 "parser.c" /* yacc.c:1646  */
+#line 2592 "parser.c" /* yacc.c:1646  */
     break;
 
   case 37:
-#line 424 "parser.y" /* yacc.c:1646  */
+#line 425 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), '/');
+  if (block_is_const_inf((yyval.blk)))
+    FAIL((yyloc), "Division by zero?");
 }
-#line 2599 "parser.c" /* yacc.c:1646  */
+#line 2602 "parser.c" /* yacc.c:1646  */
     break;
 
   case 38:
-#line 428 "parser.y" /* yacc.c:1646  */
+#line 431 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), '%');
+  if (block_is_const_inf((yyval.blk)))
+    FAIL((yyloc), "Remainder by zero?");
 }
-#line 2607 "parser.c" /* yacc.c:1646  */
+#line 2612 "parser.c" /* yacc.c:1646  */
     break;
 
   case 39:
-#line 432 "parser.y" /* yacc.c:1646  */
+#line 437 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_update((yyvsp[-2].blk), (yyvsp[0].blk), '/');
 }
-#line 2615 "parser.c" /* yacc.c:1646  */
+#line 2620 "parser.c" /* yacc.c:1646  */
     break;
 
   case 40:
-#line 436 "parser.y" /* yacc.c:1646  */
+#line 441 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_update((yyvsp[-2].blk), (yyvsp[0].blk), '%');
 }
-#line 2623 "parser.c" /* yacc.c:1646  */
+#line 2628 "parser.c" /* yacc.c:1646  */
     break;
 
   case 41:
-#line 440 "parser.y" /* yacc.c:1646  */
+#line 445 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), EQ);
 }
-#line 2631 "parser.c" /* yacc.c:1646  */
+#line 2636 "parser.c" /* yacc.c:1646  */
     break;
 
   case 42:
-#line 444 "parser.y" /* yacc.c:1646  */
+#line 449 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), NEQ);
 }
-#line 2639 "parser.c" /* yacc.c:1646  */
+#line 2644 "parser.c" /* yacc.c:1646  */
     break;
 
   case 43:
-#line 448 "parser.y" /* yacc.c:1646  */
+#line 453 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), '<');
 }
-#line 2647 "parser.c" /* yacc.c:1646  */
+#line 2652 "parser.c" /* yacc.c:1646  */
     break;
 
   case 44:
-#line 452 "parser.y" /* yacc.c:1646  */
+#line 457 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), '>');
 }
-#line 2655 "parser.c" /* yacc.c:1646  */
+#line 2660 "parser.c" /* yacc.c:1646  */
     break;
 
   case 45:
-#line 456 "parser.y" /* yacc.c:1646  */
+#line 461 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), LESSEQ);
 }
-#line 2663 "parser.c" /* yacc.c:1646  */
+#line 2668 "parser.c" /* yacc.c:1646  */
     break;
 
   case 46:
-#line 460 "parser.y" /* yacc.c:1646  */
+#line 465 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_binop((yyvsp[-2].blk), (yyvsp[0].blk), GREATEREQ);
 }
-#line 2671 "parser.c" /* yacc.c:1646  */
+#line 2676 "parser.c" /* yacc.c:1646  */
     break;
 
   case 47:
-#line 464 "parser.y" /* yacc.c:1646  */
+#line 469 "parser.y" /* yacc.c:1646  */
     { 
   (yyval.blk) = (yyvsp[0].blk); 
 }
-#line 2679 "parser.c" /* yacc.c:1646  */
+#line 2684 "parser.c" /* yacc.c:1646  */
     break;
 
   case 48:
-#line 469 "parser.y" /* yacc.c:1646  */
+#line 474 "parser.y" /* yacc.c:1646  */
     {
   jv v = block_const((yyvsp[-4].blk));
   // XXX Make gen_import take only blocks and the int is_data so we
@@ -2689,11 +2694,11 @@ yyreduce:
   jv_free((yyvsp[-1].literal));
   jv_free(v);
 }
-#line 2693 "parser.c" /* yacc.c:1646  */
+#line 2698 "parser.c" /* yacc.c:1646  */
     break;
 
   case 49:
-#line 478 "parser.y" /* yacc.c:1646  */
+#line 483 "parser.y" /* yacc.c:1646  */
     {
   jv v = block_const((yyvsp[-3].blk));
   (yyval.blk) = gen_import(jv_string_value(v), gen_noop(), jv_string_value((yyvsp[-1].literal)), 0);
@@ -2701,11 +2706,11 @@ yyreduce:
   jv_free((yyvsp[-1].literal));
   jv_free(v);
 }
-#line 2705 "parser.c" /* yacc.c:1646  */
+#line 2710 "parser.c" /* yacc.c:1646  */
     break;
 
   case 50:
-#line 485 "parser.y" /* yacc.c:1646  */
+#line 490 "parser.y" /* yacc.c:1646  */
     {
   if (!block_is_const((yyvsp[-1].blk))) {
     FAIL((yyloc), "Module metadata must be constant.");
@@ -2718,11 +2723,11 @@ yyreduce:
   block_free((yyvsp[-4].blk));
   jv_free((yyvsp[-2].literal));
 }
-#line 2722 "parser.c" /* yacc.c:1646  */
+#line 2727 "parser.c" /* yacc.c:1646  */
     break;
 
   case 51:
-#line 497 "parser.y" /* yacc.c:1646  */
+#line 502 "parser.y" /* yacc.c:1646  */
     {
   if (!block_is_const((yyvsp[-1].blk))) {
     FAIL((yyloc), "Module metadata must be constant.");
@@ -2735,173 +2740,173 @@ yyreduce:
   block_free((yyvsp[-5].blk));
   jv_free((yyvsp[-2].literal));
 }
-#line 2739 "parser.c" /* yacc.c:1646  */
+#line 2744 "parser.c" /* yacc.c:1646  */
     break;
 
   case 52:
-#line 511 "parser.y" /* yacc.c:1646  */
+#line 516 "parser.y" /* yacc.c:1646  */
     {
   (yyval.blk) = gen_function(jv_string_value((yyvsp[-3].literal)), gen_noop(), (yyvsp[-1].blk));
   jv_free((yyvsp[-3].literal));
 }
-#line 2748 "parser.c" /* yacc.c:1646  */
+#line 2753 "parser.c" /* yacc.c:1646  */