basic.zsh

basic() { echo '>'}

hooktest.zsh

# hooktest - can we add-zsh-hook inside a hook?

_ROOT=${0:A:h}
_SEPARATOR=" "
_PROMPT=(timer basic)

# join outputs of functions
_wrap() {
    local -a outputs
    for cmd in ${(P)1}; do
        (( $+functions[$cmd] )) || source ${_ROOT}/${cmd}.zsh
        (( $+functions[$cmd] )) && output="$(eval "$cmd")"
        (( $status )) || outputs+="$output"
    done

    echo ${(ps.$_SEPARATOR.)outputs}$_SEPARATOR
}

# Show left prompt
_prompt() { PROMPT=$(_wrap _PROMPT) }
add-zsh-hook precmd _prompt

timer.zsh

# timer - show the elapsed time for long running commands

zmodload zsh/datetime || return # required for `$EPOCHSECONDS`

typeset -g _command_timestamp
typeset -g _command_exec_time

# Begin to track the EPOCHSECONDS since this command is executed
_set_command_timestamp() { _command_timestamp=$EPOCHSECONDS }
add-zsh-hook preexec _set_command_timestamp

# Stores the exec time of the last command if set threshold was exceeded
_check_command_exec_time() {
  integer elapsed
  # Clear command_exec_time to avoid double rendering
  _command_exec_time=

  # Set command_exec_time if elapsed time is above _PATIENCE
  (( elapsed = EPOCHSECONDS - ${_command_timestamp:-$EPOCHSECONDS} ))
  (( elapsed > ${_PATIENCE:=0} )) && _command_exec_time=$elapsed

  # Clear timestamp
  _command_timestamp=
}
add-zsh-hook precmd _check_command_exec_time

timer() { echo $_command_exec_time }