Debug macro for janet

debug.janet

(defmacro dbg! [form]
  (let [func (first form)
        args (drop 1 form)]
    (var accum @['do])
    (var syms @[])
    (each arg args
      (let [sym (gensym)]
        (array/push accum (tuple 'def sym arg))
        (array/push syms [arg sym])))

    (array/push accum (tuple 'def 'ret (tuple func ;(map last syms))))
    (array/push accum (tuple 'printf (string/format "dbg!: %q => %%q" form) 'ret))
    (each [a s] syms
      (array/push accum (tuple 'printf "      %s => %q" (string/format "%q" a) s)))
    (array/push accum 'ret)
    (tuple/slice accum 0)))

(var foo @{})
(each x [3 4]
  (dbg! (put foo x (* x x))))

# dbg!: (put foo x (* x x)) => @{3 9}
#       foo => @{3 9}
#       x => 3
#       (* x x) => 9))))
# dbg!: (put foo x (* x x)) => @{3 9 4 16}
#       foo => @{3 9 4 16}
#       x => 4
#       (* x x) => 16