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From: cross@spitfire.i.gajendra.net (Dan Cross)
Newsgroups: comp.os.vms
Subject: Re: New VSI post on Youtube
Date: Sun, 25 Aug 2024 11:10:19 -0000 (UTC)
Organization: PANIX Public Access Internet and UNIX, NYC
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In article <vae3fe$1j523$1@dont-email.me>,
Arne Vajhøj  <arne@vajhoej.dk> wrote:
>On 8/24/2024 9:33 PM, Stephen Hoffman wrote:
>> On 2024-08-20 12:36:51 +0000, Simon Clubley said:
>>> One thing I wish was available in all languages is the ability to 
>>> return multiple values from a function call so you can return both a 
>>> status and the value(s) in one assignment. Ie: "a, b, c = 
>>> demo_function(param1, param2);".
>>>
>>> In languages with dynamic associative arrays (such as PHP), I simulate 
>>> this by returning an associative array from a function call with both 
>>> status and value fields. Makes coding _so_ much cleaner and robust.
>> 
>> For those following along at home, C supports returning a struct.
>> 
>> Languages including Swift allow returning an "optional", where you 
>> either get a value such as an object, or an indication or its absence. 
>> Swift uses the concept of "unwrapping" a result marked optional, which 
>> means you have to check before access.
>> 
>> Returning objects is more widely available, and hides a lot of this 
>> mess, as well as hiding dealing with potentially-larger data buffers. 
>> Objects and message-passing is akin to itemlist-based APIs, dragged 
>> forward a few decades.
>> 
>> In other languages, support for an optional requires explicit code, 
>> whether that might return a struct, or might return a value and a 
>> sentinel, or ilk.
>
>I don't know Swift but I will assume Swift optional is similar to
>optional in other languages.
>
>It solves the return both status and value problem. But it is
>not a general multiple return value solution. And it is really
>just a small evolution of the traditional "return null
>indicate an error".
>
> [snip overly long Java sequence]

What a failure of imagination.  When you have the Maybe monad,
it actually opens up a lot of ground for abstraction.
https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-validate/

	- Dan C.