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Welcome to the Signs wiki!

---

Sign is an interpreter and type-checker for Abstract Categorial Grammars (ACG).

Requirements : GHC must be installed

Running the REPL:

runhaskell Signs.hs

You should now see the welcome screen:

 _______ _________ _______  _     _  _______ 
(  ____ \\__   __/(  ____ \( \   ( )/  ____ \
| (    \/   ) (   | (    \/|  \  | || (    \/
| (_____    | |   | |      |   \ | || (_____ 
(_____  )   | |   | | ____ | |\ \| |(_____  )
      ) |   | |   | | \_  )| | \   |      ) |
/\____) |___) (___| (___) || |  \  |/\____) |
\_______)\_______/(_______)(_)   \_)\_______)
 v0.96                       Chris Blom 2012   

enter :help to list the available commands.

type :load opt to load the grammar defined in the opt.signs file

:load opt
loading... 	opt.signs	: OK
type checking...	      	: OK
>

If there are no errors in the grammars, we can now enter some terms:

>JOHN

The interpreter will lookup the term in the grammar, and print it's sign, along with types.

JOHN :: np = 
< "John" :: f
, John :: e
>

Any well-typed closed lambda term over abstract terms can be interpreter, for example:

>LIKES JOHN MARY

Evaluates to:

LIKES(JOHN)(MARY) :: vp = 
< "Mary" + "likes" + "John" :: f
, \e.Likes(e) /\ AG(e,Mary) /\ PAT(e,John) :: et
>