Re: Adding an ignore function to Control.Monad

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Jeff Wheeler

11 Jul 2009 11 Jul '09

3:35 a.m.

On Fri, Jul 10, 2009 at 10:10 PM, Don Stewart wrote:

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## Control.Monad.void m a -> m () Don Stewart Iavor Diatchki

For whatever it's worth, I prefer void as well, for the exact reason Don said. Indeed, 'ignore' indicates to me that the argument won't even be evaluated: it'll be ignored, and skipped. But it is, and only part --- the result --- is ignored. What about 'void' with functors? Jeff Wheeler

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Johan Tibell

11 Jul 11 Jul

4:05 a.m.

New subject: Adding an ignore function to Control.Monad

On Sat, Jul 11, 2009 at 9:35 AM, Jeff Wheeler wrote:

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On Fri, Jul 10, 2009 at 10:10 PM, Don Stewart wrote:

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## Control.Monad.void m a -> m () Don Stewart Iavor Diatchki

For whatever it's worth, I prefer void as well, for the exact reason Don said. Indeed, 'ignore' indicates to me that the argument won't even be evaluated: it'll be ignored, and skipped. But it is, and only part --- the result --- is ignored.

I also think void is clearer than ignore. -- Johan

Stephan Friedrichs

4:25 a.m.

New subject: Adding an ignore function to Control.Monad

Johan Tibell wrote:

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I also think void is clearer than ignore.

So do I. Another point is, that it's familiar from other languages; a function "void f(...)" doesn't return anything but may have an effect on the environment. Stephan -- Früher hieß es ja: Ich denke, also bin ich. Heute weiß man: Es geht auch so. - Dieter Nuhr

Malcolm Wallace

5:58 a.m.

New subject: Adding an ignore function to Control.Monad

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Johan Tibell wrote:

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I also think void is clearer than ignore.

So do I. Another point is, that it's familiar from other languages; a function "void f(...)" doesn't return anything but may have an effect on the environment.

+1. Regards, Malcolm

Magnus Therning

12 Jul 12 Jul

4:12 a.m.

New subject: Adding an ignore function to Control.Monad

Stephan Friedrichs wrote:

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Johan Tibell wrote:

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I also think void is clearer than ignore.

So do I. Another point is, that it's familiar from other languages; a function "void f(...)" doesn't return anything but may have an effect on the environment.

That depends on what languages you are familiar with, of course. To me void is a type (C/C++) while ignore is a function (OCaml) ;-) /M -- Magnus Therning (OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe

Bulat Ziganshin

4:25 a.m.

New subject: Re[2]: Re: Adding an ignore function to Control.Monad

Hello Magnus, Sunday, July 12, 2009, 12:12:01 PM, you wrote:

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That depends on what languages you are familiar with, of course. To me void is a type (C/C++) while ignore is a function (OCaml) ;-)

you can write "(void)" :) -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

Henning Thielemann

14 Aug 14 Aug

1:43 p.m.

New subject: Adding an ignore function to Control.Monad

On Sun, 12 Jul 2009, Magnus Therning wrote:

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Stephan Friedrichs wrote:

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Johan Tibell wrote:

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[...]

I also think void is clearer than ignore.

So do I. Another point is, that it's familiar from other languages; a function "void f(...)" doesn't return anything but may have an effect on the environment.

That depends on what languages you are familiar with, of course. To me void is a type (C/C++) while ignore is a function (OCaml) ;-)

In the Modula-II derivative Cluster it is named FORGET, in Modula-3 it is named EVAL. http://www.henning-thielemann.de/Cluster/Handbuch.pdf http://www.cs.tut.fi/lintula/manual/modula3/m3defn/html/eval.html

Dan Doel

11 Jul 11 Jul

4:17 a.m.

New subject: Adding an ignore function to Control.Monad

On Saturday 11 July 2009 3:35:27 am Jeff Wheeler wrote:

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On Fri, Jul 10, 2009 at 10:10 PM, Don Stewart wrote:

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## Control.Monad.void m a -> m () Don Stewart Iavor Diatchki

For whatever it's worth, I prefer void as well, for the exact reason Don said. Indeed, 'ignore' indicates to me that the argument won't even be evaluated: it'll be ignored, and skipped. But it is, and only part --- the result --- is ignored.

What about 'void' with functors?

Perhaps it should be noted that 'void' is sometimes associated with the type: data Void the 'empty' type (which isn't empty in Haskell). In typical catamorphism style, void would be its eliminator: void :: forall a. Void -> a void _ = undefined -- if you're writing Agda -- void () This, doesn't see much use in Haskell, though, so perhaps it's irrelevant. -- Dan

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participants (8)

Bulat Ziganshin
Dan Doel
Henning Thielemann
Jeff Wheeler
Johan Tibell
Magnus Therning
Malcolm Wallace
Stephan Friedrichs