Re: Proposal: rename Data.Map.fromAscList to Data.Map.unsafeFromAscList

On Apr 24, 2009, at 2:51 PM, Neil Mitchell wrote:

Hi,

I totally disagree. unsafe/unchecked means nothing other than "beware of the bogey monster", or for most Haskell users, "just another function that might launch missiles". fromAscList has the specific precondition for this function in the name. Should we call unsafeHead? uncheckedHead? mightCrashIfNotConsHead?

Adding a check for the precondition would be the ideal thing to do, but I wouldn't want to do it if it added an extra comparison or was any runtime cost at all. Perhaps adding checkedFromAscList might be acceptable, but I can't imagine anyone would call it until they'd got it wrong the first time, at which point the chances of them getting it wrong again are quite low.

Thanks

Neil

On Fri, Apr 24, 2009 at 1:36 PM, Christian Maeder wrote:

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Personally I very much hope that Haskell' will change the definition of head to a safe version and include the current head function as unsafeHead. Encouraging developers to use and write total function is probably a good thing and prevents us from having to explain all those messy corners in the Haskell language to our Ruby and Python friends. Adding a new function safeFromAscList that actually checks the precondition and returns a |Maybe (Map a b)| may sound as a nice compromise, but shouldn't all function be safe by default? I'd much rather see to version of which one is called the `unsafe' than two version of which one is called `safe'. Safe feels like a safe default. -- Sebastiaan