How to list / show all built-in functions?

Question

How can I list / show all built-in functions, similar to the :function command which lists all (non-builtin?) functions?

Answer 1

Try this:

new | put! =getcompletion('*', 'function')->filter({_, v -> v =~# '^[a-z][^#]*$'})

Broken down:

• new - Create a new window and start editing an empty file in it
• put! - Put the text from a register before the current line
• = - The expression register
• getcompletion('*', 'function') - Return a list of command-line completion for all functions
• ->filter({lambda}) - filter results from the returned list of getcompletion(...) based on the return value of {lambda}
• {_, v -> v =~# '{pattern}'} - Lambda function that returns 1 if v case sensitively matches {pattern}, else 0
• ^[a-z][^#]*$'
  • ^ - Start of string
  • [a-z] - Any lowercase letter
  • [^#]* - Any non-# character, 0 or more times
  • $ - End of String

For more info, see:

• :h :new
• :h :put
• :h getcompletion()
• :h filter()

Answer 2

I found a list in :help functions (plural) which is sufficient if there is no command. But it would be nice to find a corollary command to :function -- is there one?

The functions list is also grouped by use here: h: function-list. Eg. it lists string-functions, cursor-functions, and so on.