macro let param* {
  local status
  define status 0
  match =0 dest+==src , status param \{
     add dest,src
     define status 1
  \}
  match =0 dest==src , status param \{
     mov dest,src
     define status 1
  \}
  match =0 dest++ , status param \{
     inc dest
     define status 1
  \}
  match =0 any , status param \{
     err "SYNTAX ERROR"
  \}
}
let ax=3
let bx++
let cx=1024    

letlist
  ax=3
  bx++
  cx=1024
end letlist    

irp x,\
  ax=3, \
  bx++, \
  cx=1024 \
  {let x}    

include '80286.inc'

macro letlist
        macro ? param&
                match =end =letlist, param
                        purge ?
                else match dest+==src, param
                        add dest,src
                else match dest==src, param
                        mov dest,src
                else match dest++, param
                        inc dest
                else match any, param
                        err "SYNTAX ERROR"
                end match
        end macro
end macro

macro end?.letlist      ; I have found a small bug while writing this example.
end macro               ; These two lines are not needed if you use the latest, fixed fasmg.

letlist
  ax=3 
  bx++ 
  cx=1024 
end letlist    

Alternatively, you can use fasmg: