docs: link to functions page from filter syntax description

Author: jg-rp

CHANGELOG.md

@@ -4,7 +4,7 @@
 
 **IETF JSONPath Draft compliance**
 
-- **Behavioral change.** When applied to a JSON object, filters now have an implicit preceding wildcard selector. This is now consistent with applying filters to arrays and adheres to the IETF JSONPath Internet Draft.
+- **Behavioral change.** When applied to a JSON object, filters now have an implicit preceding wildcard selector and the "current" (`@`) object is set to each of the object's values. This is now consistent with applying filters to arrays and adheres to the IETF JSONPath Internet Draft.
 
 ## Version 0.3.0
 

README.md

@@ -264,7 +264,7 @@ $..products.*.price | $.price_cap
 The `&` operator produces matches that are common to both left and right paths. This example would select the list of products that are common to both the "footwear" and "headwear" categories.
 
 ```text
-$.categories.*[?(@.name == 'footwear')].products.* & $.categories.*[?(@.name == 'headwear')].products.*
+$.categories[?(@.name == 'footwear')].products.* & $.categories[?(@.name == 'headwear')].products.*
 ```
 
 Note that `|` and `&` are not allowed inside filter expressions.
@@ -290,7 +290,6 @@ And this is a list of areas where we deviate from the [IETF JSONPath draft](http
 - The root token (default `$`) is optional.
 - Paths starting with a dot (`.`) are OK. `.thing` is the same as `$.thing`, as is `thing`, `$[thing]` and `$["thing"]`.
 - Nested filters are not supported.
-- We don't treat filter expressions without a comparison as existence test, but an "is truthy" test.
 
 And this is a list of features that are uncommon or unique to Python JSONPath.
 

docs/functions.md

@@ -0,0 +1,7 @@
+# Filter Functions
+
+TODO:
+
+## `length()`
+
+TODO:

docs/syntax.md

@@ -134,7 +134,7 @@ Comparison operators include `==`, `!=`, `<`, `>`, `<=` and `>=`. Plus `<>` as a
 $..products[?(@.description =~ /.*trainers/i)]
 ```
 
-Filters can use [function extensions](#function-extensions) too.
+Filters can use [function extensions](functions.md) too.
 
 ### Union (`|`) and intersection (`&`)
 
@@ -149,17 +149,11 @@ $..products.*.price | $.price_cap
 The `&` operator produces matches that are common to both left and right paths. This example would select the list of products that are common to both the "footwear" and "headwear" categories.
 
 ```text
-$.categories.*[?(@.name == 'footwear')].products.* & $.categories.*[?(@.name == 'headwear')].products.*
+$.categories[?(@.name == 'footwear')].products.* & $.categories[?(@.name == 'headwear')].products.*
 ```
 
 Note that `|` and `&` are not allowed inside filter expressions.
 
-## Function extensions
-
-[Filters](#filters-expression) can call functions, be they built-in functions or custom functions. The result of a function call will be evaluated as part of the filter expression.
-
-TODO:
-
 ## Notable differences
 
 This is a list of things that you might find in other JSONPath implementation that we don't support (yet).
@@ -177,7 +171,6 @@ And this is a list of areas where we deviate from the [IETF JSONPath draft](http
 - The root token (default `$`) is optional.
 - Paths starting with a dot (`.`) are OK. `.thing` is the same as `$.thing`, as is `thing`, `$[thing]` and `$["thing"]`.
 - Nested filters are not supported.
-- We don't treat filter expressions without a comparison as existence test, but an "is truthy" test. See the "Existence of non-singular queries" example in the IETF JSONPath draft.
 
 And this is a list of features that are uncommon or unique to Python JSONPath.
 

mkdocs.yml

@@ -45,6 +45,7 @@ nav:
       - Advanced Usage: "advanced.md"
   - Guides:
       - JSONPath Syntax: "syntax.md"
+      - Filter Functions: "functions.md"
       - Async Support: "async.md"
   - API Reference:
       - High Level API: "api.md"