Comments for ...cwbowron...

Comment on Toronto by paul

paul — Thu, 26 Aug 2010 17:55:34 +0000

Nice video, I love toronto, queen street… I liked the glass floor in the CN tower, and the indian food. any how, I thought I would write since I found your site due to the fubar plugin thinggy.

have a great day

Comment on Deer! by Curt

Curt — Tue, 17 Aug 2010 14:41:33 +0000

Very cool..I am not cleaning up deer scat though, lol

Comment on From the Archives: Poetry by Jared

Jared — Sun, 07 Feb 2010 19:09:30 +0000

Nice piece. You should perform it at the next SpitFire poetry event in East Lansing. Have you written anything else since?

Comment on From the Archives: TI-85 Password Protection by Ethan

Ethan — Thu, 03 Dec 2009 15:59:19 +0000

If only TI had an app store in 1996, you could have made those Wads of Cash

Comment on VLC and PLT Scheme [n+1] by cwbowron

cwbowron — Sat, 21 Nov 2009 13:15:20 +0000

Makes sense.

Previous versions of VLC worked with file://localfile.ext, so it took me a while to figure out that the latest requires the 3 slashes.

Comment on VLC and PLT Scheme [n+1] by Ethan

Ethan — Sat, 21 Nov 2009 00:41:14 +0000

Two slashes after the protocol, if the hostname is omitted it defaults to localhost and the third slash denotes the start of the path

Comment on Multiple Return Values by EAsports

EAsports — Sun, 31 May 2009 20:45:38 +0000

Links to the some of the comp.lang.scheme discussions about this are at http://www.archivum.info/comp.lang.scheme/2009-02/msg00092.html

Comment on Multiple Return Values by cwbowron

cwbowron — Sun, 31 May 2009 18:49:50 +0000

FWIW, you wouldn’t say (cadr (floor x)). Floor returns multiple values, it DOES NOT return a list with multiple values. I don’t know that you are understanding multiple value returns completely.

Also, given the way that multiple values work in CL, (equal? 3.0 (floor 3.5)) returns T. The second return value from floor is discard since it is not used.

If you say (let ((foo (floor 3.6)) (print floor))) it will print out 3.0… If you want to capture the second value, you use use the multiple-value-bind construct, such as (multiple-value-bind (foo bar) (floor 3.5) …)

Comment on Multiple Return Values by vgable

vgable — Fri, 29 May 2009 23:11:54 +0000

FWIW, if -objectForKey: returns nil, then there's nothing in the dictionary under that key. There's a sentinel value: [NSNull null] for representing nil in a Cocoa collection (you can't put nil in any of them, including NSArray). I'm not a huge fan of sentinel values, but as you pointed out, it's rare that the distinction between having nil or not having anything matters. I don't think I've ever used NSNull in any of my code. There's also an argument for having a -dictionaryContainsKey: method... The floor example is a bit scary to me. I don't quite see the reason for making floor so complex. There are simple operations like "is this an integer?", or "x - floor(x)" that give the same result more clearly... (cadr (floor x)) just doesn't say "floor of x is equal to x" to me...

Comment on Multiple Return Values by cwbowron

cwbowron — Fri, 29 May 2009 19:20:45 +0000

As far as using multiple value functions where one expects to use a single value function, Common Lisp handles that case well, IIRC, it just discards all but the first value. For example, the floor operator in CL returns two values… 1 – the value you probably want and 2 – wait it dropped…. You can still use floor in a map, it just uses the first value… (floor 3.5) returns 3.0 and .5, where as (map ‘list #’floor (list 3.5)) returns (3).

As far as my hash example, yes I mean that the first value returned is success or failure and the second value is the actual mapped value.

@V – The problem with if([dictionary objectForKey:someKey]){} as far as I was mentioning was that you don’t know whether the key was not in the dictionary or whether the value for the key was actually nil. But as I pointed out, I’m not sure when you would handle those cases differently.