# Guessing the implementation of combinators

Posted on May 16, 2012

I completed Oleg’s de-typechecker and put it on hackage as `Guess.Combinator`

.

http://hackage.haskell.org/packages/archive/guess-combinator/0.1.1/doc/html/Guess-Combinator.html

The original article had left part of the code as an exercise for the reader. Completing it on your own would be great practice for learning type-level programming.

http://www.haskell.org/pipermail/haskell/2005-March/015423.html

How is this useful? Take the `$-`

operator for example.

http://www.atnnn.com/p/haskell-nameless-parameters/

It can now be written as

```
$-) ∷ (d → a → e) → (e → k) → d → a → k
($-) = combinator (
```

Haskell is magic!