[m-users.] How to avoid warning about highly ambiguous overloading

[Zoltan Somogyi]

While X = map.init could be a reference to either the function
or the predicate version of map.init, map.init(X) can only be a reference
to the predicate version. In many cases, this technique will avoid
ambiguity with shorter code than using explicit type qualification.

Zoltan.

-------- Original message --------
From: Dirk Ziegemeyer <dirk at ziegemeyer.de> 
Date:2016/07/19  2:14 PM  (GMT+01:00) 
To: Mark Brown <mark at mercurylang.org> 
Cc: Mercury Users <users at lists.mercurylang.org> 
Subject: Re: [m-users.] How to avoid warning about highly ambiguous
 	overloading 

Hi Mark,

>> I create several emtpy maps with the function map.init/0 and mercury warns me about highly ambiguous overloading.
> 
> Note that this can occur as a consequence of other errors, so it can
> help to fix any other errors first before tackling the ambiguous
> overloading.
> 
>> Can I use explicit type qualification to tell Mercury that I mean the function map.init/0 instead of the predicate map.init/1?
> 
> Yes. If you want map.init to mean the function which returns, say,
> map(a, b), then write
> 
>    map.init : map(a, b)

Thank you for helping me with the syntax of explicit type qualification. This works perfectly.

Dirk
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