Add parameter highlights to Erlang

This doesn't work robustly (within pattern matches). Only regular
bindings are highlighted as parameters. In order to highlight all
parameters even in matches, we would need an arbitrary nesting operator
in queries which doesn't exist yet in tree-sitter.

runtime/queries/erlang/highlights.scm

@@ -65,6 +65,37 @@
 (function_capture module: (atom) @namespace)
 (function_capture function: (atom) @function)
 
+; Ignored variables
+((variable) @comment.discard
+ (#match? @comment.discard "^_"))
+
+; Parameters
+; specs
+((attribute
+   name: (atom) @keyword
+   (stab_clause
+     pattern: (arguments (variable) @variable.parameter)
+     body: (variable)? @variable.parameter))
+ (#match? @keyword "(spec|callback)"))
+; functions
+(function_clause pattern: (arguments (variable) @variable.parameter))
+; anonymous functions
+(stab_clause pattern: (arguments (variable) @variable.parameter))
+; parametric types
+((attribute
+    name: (atom) @keyword
+    (arguments
+      (binary_operator
+        left: (call (arguments (variable) @variable.parameter))
+        operator: "::")))
+ (#match? @keyword "(type|opaque)"))
+; macros
+((attribute
+   name: (atom) @keyword
+   (arguments
+     (call (arguments (variable) @variable.parameter))))
+ (#eq? @keyword "define"))
+
 ; Records
 (record_content
   (binary_operator
@@ -105,9 +136,6 @@
   name: (_) @keyword.directive)
 
 ; Comments
-((variable) @comment.discard
- (#match? @comment.discard "^_"))
-
 (tripledot) @comment.discard
 
 [(comment) (line_comment) (shebang)] @comment

runtime/queries/erlang/locals.scm

@@ -0,0 +1,30 @@
+; Specs and Callbacks
+(attribute
+  (stab_clause
+    pattern: (arguments (variable) @local.definition)
+    ; If a spec uses a variable as the return type (and later a `when` clause to type it):
+    body: (variable)? @local.definition)) @local.scope
+
+; parametric `-type`s
+((attribute
+    name: (atom) @_type
+    (arguments
+      (binary_operator
+        left: (call (arguments (variable) @local.definition))
+        operator: "::") @local.scope))
+ (#match? @_type "(type|opaque)"))
+
+; macros
+((attribute
+   name: (atom) @_define
+   (arguments
+     (call (arguments (variable) @local.definition)))) @local.scope
+ (#eq? @_define "define"))
+
+; `fun`s
+(anonymous_function (stab_clause pattern: (arguments (variable) @local.definition))) @local.scope
+
+; Ordinary functions
+(function_clause pattern: (arguments (variable) @local.definition)) @local.scope
+
+(variable) @local.reference