View source for Shooting your self in the foot

The following list was proposed by members of Haskell-Cafe.

The original thread can be found 
[http://www.haskell.org/pipermail/haskell-cafe/2008-October/048506.html here].

How to Shoot Your Self in the Foot With Haskell: Putting the unsafe in unsafePerformIO!

* You shoot the gun, but the bullet gets trapped in the IO monad.
* Couldn't match expected type 'Deer' against inferred type 'Foot'.
* While compiling your program the compiler produces a type error long enough to overflow a kernel buffer, overwrite the trigger control register and shoot you in the foot.
* After trying to decipher the type errors from the compiler, your head explodes.
* After you've finally found a way to circumvent the type system and shoot yourself in the foot, Oleg appears out of nothing and shoots you in the foot for coming up with it before him.
* You shoot the gun but nothing happens (Haskell is pure, after all).
* Your foot is fine, until you try to walk on it, at which point it becomes mangled.
* You have a shootFoot function which you've proven correct. QuickCheck validates it for arbitrary you-like values. It will be evaluated only when you end up at the hospital. You hope this doesn't come to pass, as it actually returns a bullet-ridden copy of yourself and you don't want to be garbage-collected.
* <haskell>foreign import ccall "shootparts.h shootfoot" shoot_foot :: Gun -> Programmer -> IO ()</haskell>
* <haskell>shootSelfInFoot = unsafePerformIO . shoot . foot $ self -- Shoot self in foot 0 or more times depending on evaluation order</haskell>
*  No instance for (Target Foot)<br />arising from use of `shoot' at SelfInflictedInjury.hs:1:0<br />Possible fix: add an instance declaration for (Target Foot)<br />In the expression: shoot foot
* You go to shoot yourself in the foot but the bullet is in the ST monad and the gun is in the IO monad, so you can't.
* You ask Haskell to shoot you in the foot but by the rules of lazy evaluation you don't need the result yet so it doesn't happen.
* You decide to shoot yourself in the foot but get distracted devising a ballistics algebra and wondering if you can do the calculations in the type system.
* You want to shoot yourself in the foot but realize there is no Gun datatype so use Arrows instead.
* You shoot in the direction of your foot, but since you are inside the STM monad you can just retry until you figure out what to do.
* You shoot yourself in the foot, but you are perfectly fine as long you just don't evaluate the foot.
* You shoot yourself in the foot, but nothing happens unless you start walking.
* Don't forget about memory consumption! If you don't look, the bullet causes heap overflow. If you look, the bullet causes stack overflow.
* You *appear* to have deliberately shot yourself in the foot, and yet your program actually runs perfectly OK due to lazy evaluation. (So long as you remember to not look at your foot...)
* You aim the gun at your foot, pull the trigger and remove the clip. When you look at your undamaged foot, the hammer clicks on an empty barrel.

[http://www-users.cs.york.ac.uk/susan/joke/foot.htm This above list is inspired by this list.]

[[Category:Humor]]