Kotlin - Differens

Kotlin extractor

The Kotlin extractor maps tree-sitter Kotlin CST nodes to canonical concepts. The Kotlin grammar declares no field names at all, so every name is recovered from the first identifier-like child: class names from type_identifier, function and variable names from simple_identifier.

Detected concepts

tree-sitter node type	Canonical concept
`class_declaration`	Class
`function_declaration`	Function
`property_declaration`	Variable
`variable_declaration`	Variable
`type_alias`	TypeDef
`import_header`	Import
`package_header`	Namespace
`call_expression`	CallExpression
`assignment`	Assignment
`jump_expression`	Return
`if_expression`	IfBlock
`when_expression`	SwitchBlock
`string_literal`	string_literal

Example

Renaming a function:

// old.kt
class Counter { fun total(n: Int): Int { return n + 1 } }

// new.kt
class Counter { fun sum(n: Int): Int { return n + 1 } }

Running differens old.kt new.kt:

~ renamed function `total` to `sum` in class `Counter`

Known limitations

The grammar’s missing field names mean label recovery is positional: a declaration with two identifier children can mislabel in exotic syntax.
Extension functions report as functions; the receiver type is part of the structure, not the name.