Evolution of a Hoon Programmer

fac.hoon

:: Hoonlet
::
|=  n=@
?:  =(n 0)
  1
(mul n $(n (dec n)))
::
:: Commie Hoontard
::   (...daydreaming of his very own Type 59...)
::
|=  n=@
(roll (gulf 1 n) mul)
::
:: Nazi Hoontard
::  (...hook, line, and sinker...)
::
|=  n=@
(reel (gulf 1 n) mul)
::
:: Accumulating Hoontard
::  (...former Haskell programmer...)
::
|=  n=@
=-  (go n 1)
^=  go
|=  [n=@ acc=@]
?-  n
  ~  acc
  @  (. (dec n) (mul acc n))
==
::
:: Iterative Hoontard
::  (...lost without his lööps; prefers "mutating" the subject...)
::
|=  n=@
=<  (for init done next)
|%
++  for
  |=  [i=[@ @] d=$-(@ ?) n=$-([@ @] [@ @])]
  ?:  (d -.i)
    +.i
  =.  i  (n i)
  $
++  init
  [0 1]
++  done
  |=  i=@
  =(i n)
++  next
  |=  [i=@ m=@]
  =.  i  +(i)
  =.  m  (mul m i)
  [i m]
--
::
:: Tacit Hoontard
::  (...sneers in your face, spreading his wide wings...)
::
|=(@ ?:(=(+< *@) +(*_+<) (mul +< $(+< (dec +<)))))
::
:: Pointless Hoontard
::  (...beyond the gateless gate...)
::
(cork (cury gulf 1) (cury (curr (fold @ @) mul) 1))
::
:: Obscurantist Hoontard
::   (...a real ass; needs more fiber in his diet...)
::
!.  |*  n=_0  =>  |.  %-
flop  %+  spun  %-  gulf
[.(- =(+ -))]:`n  |:  ;;
[@ @]   !=(...)  =<  .^.
(mul &2)   :(mule ,:-:$)
::
:: Continuation-passing Hoontard
::  (...kicked out of culinary school; always plotting some new scheme...)
::
|=  n=@
%.  [(bake same @) n]
|=  [f=$-(@ @) n=@]
?:  =(n 0)  (f 1)
%=  $
  f  (bake (cork f (cury mul n)) @)
  n  (dec n)
==
::
:: Church-going Hoontard
::  (...a real fixer-upper...)
::
|^  (y fac)
++  y
  |=  f=$-($-(@ @) $-(@ @))
  |=  x=@
  ((f .) x)
++  fac
  |=  f=$-(@ @)
  |=  x=@
  ?:  =(x 0)  1
  (mul x (f (dec x)))
--
::
:: Sugar-free Hoontard
::   (...former Assembly programmer; big Rothko fan...)
::
:-  ^=  n    0  .   |%  ++    $
?:  .=  n    0  .+   0  =>   :-
^=   r  %=   $  n   =>  :-  dec
.   =>  %=   -  +<   n  ==    $
==   .  =>  :-  mul  .  =>   %=
-   +<  :-   n  r   ==  $    --
::
:: Nockchad
::  (...if you wish to compute factorial from scratch,
::      you must first invent the universe...)
::
=>  ~  :: look ma, no subject!
|^  fac
++  dec
  |=  a=@
  =|  b=@
  |-
  ?:  =(a +(b))  b
  $(b +(b))
++  add
  |=  [a=@ b=@]
  ?:  =(0 a)  b
  $(a (dec a), b +(b))
++  mul
  |=  [a=@ b=@]
  =|  c=@
  |-
  ?:  =(0 a)  c
  $(a (dec a), c (add b c))
++  fac
  |=  n=@
  ?:  =(n 1)  1
  (mul n $(n (dec n)))
--
::
:: Unary Nockchad
::  (...Martian education tends to liberate one from petty concerns,
::      e.g. the efficiency of hardware-based integers...)
::
=>  ~
|^
|=  n=@
(decel (fac (incel n)))
++  inc  |=(* `+6)
++  dec  |=(^ +13)
++  add
  |=  [xs=* ys=*]
  ?@  xs  ys
  $(xs (dec xs), ys (inc ys))
++  mul
  |=  [xs=* ys=*]
  =|  zs=*
  |-
  ?@  xs  zs
  $(xs (dec xs), zs (add ys zs))
++  fac
  |=  l=*
  ?@  l  (inc l)
  (mul l (fac (dec l)))
++  incel
  |=  n=@
  =|  i=@
  |-
  ?:  =(n i)  ~
  (inc $(i +(i)))
++  decel
  |=  n=*
  =|  i=*
  |-
  ?:  =(n i)  0
  +($(i (inc i)))
--