Support numbers and boolean in join (fix #930)

docs/content/3.manual/manual.yml

@@ -1446,11 +1446,17 @@ sections:
           running `split("foo") | join("foo")` over any input string
           returns said input string.
 
+          Numbers and booleans in the input are converted to strings.
+          Null values are treated as empty strings. Arrays and objects
+          in the input are not supported.
+
         examples:
           - program: 'join(", ")'
             input: '["a","b,c,d","e"]'
             output: ['"a, b,c,d, e"']
-
+          - program: 'join(" ")'
+            input: '["a",1,2.3,true,null,false]'
+            output: ['"a 1 2.3 true  false"']
 
       - title: "`ascii_downcase`, `ascii_upcase`"
         body: |

src/builtin.jq

@@ -59,7 +59,10 @@ def values: select(. != null);
 def scalars: select(. == null or . == true or . == false or type == "number" or type == "string");
 def scalars_or_empty: select(. == null or . == true or . == false or type == "number" or type == "string" or ((type=="array" or type=="object") and length==0));
 def leaf_paths: paths(scalars);
-def join($x): reduce .[] as $i (null; (.//"") + (if . == null then $i else $x + $i end))//"";
+def join($x): reduce .[] as $i (null;
+            (if .==null then "" else .+$x end) +
+            ($i | if type=="boolean" or type=="number" then tostring else .//"" end)
+        ) // "";
 def _flatten($x): reduce .[] as $i ([]; if $i | type == "array" and $x != 0 then . + ($i | _flatten($x-1)) else . + [$i] end);
 def flatten($x): if $x < 0 then error("flatten depth must not be negative") else _flatten($x) end;
 def flatten: _flatten(-1);

tests/jq.test

@@ -1259,13 +1259,29 @@ try -. catch .
 "very-long-string"
 "string (\"very-long-...) cannot be negated"
 
-try join(",") catch .
+join(",")
-["1",2]
+["1",2,true,false,3.4]
-"string (\",\") and number (2) cannot be added"
+"1,2,true,false,3.4"
+
+.[] | join(",")
+[[], [null], [null,null], [null,null,null]]
+""
+""
+","
+",,"
+
+.[] | join(",")
+[["a",null], [null,"a"]]
+"a,"
+",a"
 
 try join(",") catch .
 ["1","2",{"a":{"b":{"c":33}}}]
-"string (\",\") and object ({\"a\":{\"b\":{...) cannot be added"
+"string (\"1,2,\") and object ({\"a\":{\"b\":{...) cannot be added"
+
+try join(",") catch .
+["1","2",[3,4,5]]
+"string (\"1,2,\") and array ([3,4,5]) cannot be added"
 
 {if:0,and:1,or:2,then:3,else:4,elif:5,end:6,as:7,def:8,reduce:9,foreach:10,try:11,catch:12,label:13,import:14,include:15,module:16}
 null