Move to the beginning of line while in Insert mode

Question

I know that I can use either:

1. Home in insert mode
2. Esc + i to exit insert mode and enter it again, effectively going to th

Answer 1

A shortcut that has worked for me (both muscle memory and intuitiveness) is to map __ (which is a double _) to "insert at start of current line".

Rationale:

• _ already goes to the start of line
• in vim, doubling anything is a very common way of doing that "to this line"
• double _ doesn't conflict with any motions (you're already at the start of line)
• your hand is already in the right place if you went to the beginning of the line and now want to insert.

vimscript:

"insert at start of current line by typing in __ (two underscores)
function DoubleUnderscore()
    if v:count == 0 && getcurpos()[2] == 1
        :silent call feedkeys('I', 'n')
    else
        :silent call feedkeys('^', v:count + 'n')
    endif
endfunction
nnoremap  _ :call DoubleUnderscore()

It's this complicated because the easy alternative nnoremap __ _I causes vim to delay on pressing _ to distinguish between _ and __.