Talk:Jensen's Device
It is amazing how wrong some ideas of early computing were. Fortunately none of modern languages really supports this mess. --Dmitry-kazakov 11:53, 22 November 2008 (UTC)
I don't think the guys in the 1960's had a monopoly on bad ideas... take the new "\" (back slash) operator in PHP[1] as an example. Fortunately, every now and then, a good idea floats to the top, the trick is being able to spot the good idea early and rewind all the bad ideas even earlier. NevilleDNZ 15:01, 22 November 2008 (UTC)
Seeing an entry on Jensen's Device just floats my boat.
Not knowing much about ALGOL60, I'm curious about its semantics -- why is i declared twice? When iterating over i, is that value being assigned local to sum, or is it being assigned in sum's caller? --Saccade 21:50, 5 May 2011 (UTC)
iis passed by reference tosum, the "first declaration" represents the declaration of the storage and the "second declaration" is the declaration of the type of the argument (much like a K&R C parameter list) in the parameters forsum. --Rdm 21:57, 5 May 2011 (UTC)
- Algol 60 actually has no call-by-reference, and
iis passed by name (the default in Algol 60). What is shown clearly here is that in Algol 60 you can pass an L-value by name, and an assignment to that parameter will assign to whatever the caller passed. Most later languages don't have call-by-name and therefore use call-by-reference or something like it fori. Scala supposedly has call-by-name, but apparently does not have this L-value-passing feature of Algol 60's call-by-name, so I guess Scala's "call-by-name" is more along the lines of Algol 68's PROC parameters. Antonertl (talk) 08:05, 17 March 2024 (UTC)
- Algol 60 actually has no call-by-reference, and
This one is great for elucidating the properties of call-by-name and how one replaces call-by-name in later programming languages, very much in line with the purpose of rosettacode. I think it would have been even greater if several uses of sum had been given, making it harder to move functionality between caller and callee; E.g., the example Sum(i, l, m, Sum(j, l, n, A[i,j])) might have been instructive, but that's water down the river. Antonertl (talk) 08:22, 17 March 2024 (UTC)