Get current directory (without full path) in Fish Shell - prompt

Question

A buddy of mine finally got me to start using Fish Shell and I'm trying to set it up similar to how I had Bash. The PS1 in my .bash_profile listed the current directory I was in, followed by a >. It, however, wasn't the absolute path (e.g. /Users/me/Documents/... or ~/Documents/...). If I was in /Users/me/Documents/projects/Go/project1/, the prompt would simply say project1 >.
Is there a Fish Shell alternative to the \W substitution available for Bash? Again, I just want the folder I'm in, not the full path. I know you can use the echo (pwd) for all that.
I have looked into the basename program, and echo "${PWD##*/}", but these appear to only work in Bash.

Answer 1

Taken from #Jubobs' answer:
basename is just a Unix utility; it's not associated to a particular shell, and should work equally well in Bash and Fish.
It appeared I was using basename in the wrong context, and without a suffix.
This was solved by using the following:
function fish_prompt
echo (basename $PWD) "><> "
end

Answer 2

An alternative: fish ships with a function called prompt_pwd which displays /Users/me/Documents/projects/Go/project1/ as ~/D/p/G/project1
function fish_prompt
echo (prompt_pwd) "><> "
end

Answer 3

The complete code of prompt_pwd.fish is below. You must put it inside the directory ~/.config/fish/functions/
function prompt_pwd --description "Print the current working directory, shortened to fit the prompt"
set -q argv[1]
and switch $argv[1]
case -h --help
__fish_print_help prompt_pwd
return 0
end
# This allows overriding fish_prompt_pwd_dir_length from the outside (global or universal) without leaking it
set -q fish_prompt_pwd_dir_length
or set -l fish_prompt_pwd_dir_length 1
# Replace $HOME with "~"
set realhome ~
# #EDITED by Thiago Andrade
set tmpdir (basename $PWD)
set -l tmp (string replace -r '^'"$realhome"'($|/)' '~$1' $tmpdir)
# ORIGINAL VERSION
# set -l tmp (string replace -r '^'"$realhome"'($|/)' '~$1' $PWD)
if [ $fish_prompt_pwd_dir_length -eq 0 ]
echo $tmp
else
# Shorten to at most $fish_prompt_pwd_dir_length characters per directory
string replace -ar '(\.?[^/]{'"$fish_prompt_pwd_dir_length"'})[^/]*/' '$1/' $tmp
end
end
Then you'll see something like this

Answer 4

This is my function in
~/.config/fish/functions/prompt_pwd.fish
and this seems to work fine
function prompt_pwd
set -q argv[1]
and switch $argv[1]
case -h --help
__fish_print_help prompt_pwd
return 0
end
set -q fish_prompt_pwd_dir_length
or set -l fish_prompt_pwd_dir_length 1
set ttmp $PWD
set ttmp (string replace -r '^'$HOME'($|/)' '~$1' $PWD)
set -l tmp (basename $ttmp)
if [ $fish_prompt_pwd_dir_length -eq 0 ]
echo $tmp
else
string replace -ar '(\.?[^/]{'"$fish_prompt_pwd_dir_length"'})[^/]*/' '$1/' $tmp
end
end