Haskell - wildcard use on right side of guard in patterns -

Haskell - wildcard use on right side of guard in patterns -

January 15, 2013

Let's say I have such code:

  test pattern | Pattern == (_, no (wire_)) = 1 | Pattern == (_, and (wire_) (wire_)) = 2 | Otherwise, = 0

Where I am trying to match it against one of the many possibilities, some with one ("wire"), some of the two I have the actual input For example: ("p", not (wire "x")). I would like a pattern which can accept any letter as input (with what I was hoping _) and disappointingly failed (invalid _). Is it possible to do this in Haskell?

OK, it makes a lot of sense after editing.

== Compare value , but _ is an pattern . Patterns only appear in the following syntax references:

Left side (pattern) binding, i.e. "what is = " at the top level or where block or let expression or command (in do notation);
left of
-> In case

   in  / code> expression;  
 Functions binding or lambda ( \ ) as a formal argument for functions in expressions.

  (I hope I have not forgotten any!) In your case, you can just get what you write by typing 
   test (_, No (wire_)) = 1 test (_, and (wire_) (wire_)) = 2 test _ = 0  
 
  You can type " What can the right version of pattern == ask for (_, no (wire_))  ". Well, you can write: 
   (_ _ _ _ _ _ _tn_n_n_not_not_not_not_id=2) case pattern of --------- _ _> ------------------------------------ >


















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