Multiply, substract with custom types

pkg/yqlib/doc/operators/add.md

@@ -7,6 +7,8 @@ Add behaves differently according to the type of the LHS:
 
 Use `+=` as append assign for things like increment. Note that `.a += .x` is equivalent to running `.a = .a + .x`.
 
+Add is not (yet) supported for maps - however you can use merge `*` which will have a similar effect...
+
 ## Concatenate and assign arrays
 Given a sample.yml file of:
 ```yaml
@@ -266,7 +268,7 @@ cat
 ```
 
 ## Custom types: that are really strings
-when custom tags are encountered, yq will try to decode the underlying type.
+When custom tags are encountered, yq will try to decode the underlying type.
 
 Given a sample.yml file of:
 ```yaml
@@ -284,7 +286,7 @@ b: !goat _meow
 ```
 
 ## Custom types: that are really numbers
-when custom tags are encountered, yq will try to decode the underlying type.
+When custom tags are encountered, yq will try to decode the underlying type.
 
 Given a sample.yml file of:
 ```yaml

pkg/yqlib/doc/operators/headers/add.md

@@ -6,3 +6,5 @@ Add behaves differently according to the type of the LHS:
 * string scalars: concatenate
 
 Use `+=` as append assign for things like increment. Note that `.a += .x` is equivalent to running `.a = .a + .x`.
+
+Add is not (yet) supported for maps - however you can use merge `*` which will have a similar effect...

pkg/yqlib/doc/operators/multiply-merge.md

@@ -410,3 +410,44 @@ thing: foobar_thing
 b: foobarList_b
 ```
 
+## Custom types: that are really numbers
+When custom tags are encountered, yq will try to decode the underlying type.
+
+Given a sample.yml file of:
+```yaml
+a: !horse 2
+b: !goat 3
+```
+then
+```bash
+yq eval '.a = .a * .b' sample.yml
+```
+will output
+```yaml
+a: !horse 6
+b: !goat 3
+```
+
+## Custom types: that are really maps
+Custom tags will be maintained.
+
+Given a sample.yml file of:
+```yaml
+a: !horse
+  cat: meow
+b: !goat
+  dog: woof
+```
+then
+```bash
+yq eval '.a = .a * .b' sample.yml
+```
+will output
+```yaml
+a: !horse
+  cat: meow
+  dog: woof
+b: !goat
+  dog: woof
+```
+

pkg/yqlib/doc/operators/subtract.md

@@ -111,3 +111,21 @@ a: 2
 b: 4
 ```
 
+## Custom types: that are really numbers
+When custom tags are encountered, yq will try to decode the underlying type.
+
+Given a sample.yml file of:
+```yaml
+a: !horse 2
+b: !goat 1
+```
+then
+```bash
+yq eval '.a -= .b' sample.yml
+```
+will output
+```yaml
+a: !horse 1
+b: !goat 1
+```
+