Is frtime supposed to handle programs like this?

['John Clements' via dev-redirect]

I was messing around with Father Time today and wrote this program:

(require 2htdp/image)

(square
(- seconds 1564512004)
"solid"
"blue”)

I expected to see a growing blue square, but instead got:

.../lang/prim.rkt:24:44: square: expects a non negative real number as first argument, given (signal 145 '() #f #<procedure:...ime/lang-ext.rkt:646:20> 2 #<continuation-mark-set> #<parameterization> (list (signal 1564512149 '(#<weak-box>) #f #<procedure:...ime/lang-ext.rkt:467:23> 1 #<continuation-mark-set> #<parameterization> '()) 156451…

Somehow the “I’m a signal but I’m also a number” abstraction didn’t quite flow through the “square” primitive. Is this supposed to work?

John

[Gregory Cooper]

Hi John,

It's been several years since I've looked at this, but what happens if you change the require line to:

(require (lifted (only-in 2htdp/image square) square))

(and, I guess, update the constant that you're subtracting from `seconds`)?

--Greg

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['John Clements' via dev-redirect]

Yes, this does exactly what I expected the original to do. Thanks!

John

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['John Clements' via dev-redirect]

Also, in the “no good deed goes unpunished” vein, do you have any idea why the tetris demo doesn’t work on recent versions of DrRacket? More specifically, the arrow the arrow keys don’t seem to have any effect on the game, though hitting a non-arrow-key results in a beep as expected. This is on MacOS, and I see the problem both in the current version (release candidate) and 7.3 and 6.11, which are all the versions I tried. Might be something simple…

John

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[Gregory Cooper]

It works for me in 7.3 on a recent version of MacOS, as long as I click in the graphics window before pressing the keys.