Programming language design checklist

What does a programming language need? Here is a list of everything I could come up with, with no details.

Mostly in order:

Basic datatypes
- Numbers
  - Integer
  - Float
- Boolean
- String
- Null
Comments
- Single line
- Multiline
Operators
- +, -
- *, /, **
- %
- ==, !=
- and, or (with short-circuiting)
- bitwise operators: &, |, ~, ^
- <, >, <=, >=
Variables
- Declaration
- (Re)assignment
- Referencing
Conditionals
- If
- While
- Repeat-until
- For
- Continue, break
- Switch/case/when
- Goto (it has valid uses)
Scoping
- Lexical scope
- Block statement
Functions
- With parameters
- With return value
- Closures
- Anonymous functions
  - Ruby-style blocks
- Named arguments
Constants
Garbage collection
Structure types
- Struct
- Classes
  - Methods
  - Traits, mixins
  - Accessors
  - Inheritance (maybe)
Equality and comparison
Collection types
- Array/List
- Dictionary/Map/Hash
- Set
- Range
- Tuple
Collection syntax/methods
- Iteration
- map/collect
- filter/select/reject
- fold/reduce/inject
Native functions
- IO
  - Write
  - Read
  - Formatted print
Standard library
- ???
- IO
- Parsing
  - JSON
  - CSV
  - …
Further
- String interpolation
- Modules
- Testing
- Source code formatting
Maybe
- List comprehensions
- Destructuring
- Pattern matching
- Concurrency
- Type system
- Extension methods
- Comptime
- Macros
- Build system
- Package manager
- LSP
- Code/test coverage

See also