Argument matching

Michael O'Brien mob at
Fri May 9 11:06:14 PDT 2008

There is a problem with that.

If it is an error to provide too many actual parameters to a function  
with typed formal parameters, then you either must supply the correct  
number of args or not type the args.

A use case that demonstrates the problem is the Array.some callback.  
Usually it is supplied with only one argument -- the element. So if a  
user declares this callback with type annotations, the call will fail  
as the iterator must supply 3 arguments.

So you can't have a callback with just one typed argument for the  
callback. You must either have one untyped arg or 3 typed arguments.


On May 9, 2008, at 10:58 AM, David Mandelin wrote:
> Lars Hansen wrote:
>> I would expect excess arguments to typed functions to be ignored
>> silently,
>> as they can be picked up by 'arguments' inside the function.
> Is there any possibility of making whether a function takes extra
> arguments part of its type? It seems kind of unfortunate not to be  
> able
> to report an error when too many args are given, which is a pretty
> common mistake and usually indicates a bug.
> Dave
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