Examples

If you have not read the syntax reference yet, it may be good to do first

By feature

Looking for one specific operator or meta-key? Jump straight to the page that demonstrates it.

Feature	What it does	Shown in
+ append	add to the end of an array	Bench-Category, Item-Category, Droplists
- prepend	add to the front of an array	Prepend-Array
? fill-if-absent	set a key only if it is missing	Fill-If-Absent
null delete	remove a key, value, or recipe	Removing-Values
~ element merge	merge into one element of an array	Match-Array-Element
$Match	locate which array element to merge	Match-Array-Element
$Requires	apply only if certain packs are installed	Parent-Override, Droplists
$Priority	decide the winner when patches conflict	Quality-Override
nested merge	change one field deep inside an object	Recipe-Change, Player-Stat
field replace	overwrite a single scalar value	Quality-Override
forward reference	name an id from a later-loading pack	Load-Order
slot retarget	point one interaction slot at another handler	Replace-Interaction

By scenario

#	You want to...	Key technique
1	Make one weapon work locally AND inside another mod	reparent with $Requires, null the local interactions
2	Add a category to a crafting bench	Categories+ array append
3	Give the player a new or bigger stat (like Mana)	patch an Entity/Stats definition
4	Point an item's interaction at another mod's internal one	replace an Interactions slot value
5	Change the quality of a block or armor piece	single-field replace
6	Reference particles defined in a later-loading pack	json reference + re-merge on register
7	Remove a field, resistance, or recipe	null delete
8	Add to a droplist or wire up a new one	Containers+ append, repoint DropList
9	Change a crafting recipe's ingredients or bench	nested object merge
10	Put an item into a creative or crafting category	Categories+ on the item
11	Override one element inside an array	~ element merge + $Match
12	Add a stat only if the item doesn't already have it	? fill-if-absent
13	Put your entries at the front of an array	- prepend

What Patchly can and cannot patch (for now)

Patchly only patches .json assets. The .patch path mirrors the target with .json swapped for .patch.

Patchable (.json)	Not patchable
Items, blocks, recipes, droplists, stat definitions, interactions, entity configs	.particlesystem, .particlespawner, .blockymodel, .blockyanim, .png, .lang

For a non-json asset, ship a normal full file in your pack instead of a .patch. You can still patch the .json that references it (see Particles And Load Order).