[Openmcl-devel] Mark Kantrowitz infix.lisp easter egg?

Joshua TAYLOR joshuaaaron at gmail.com
Sat Dec 3 02:08:34 UTC 2011


On Fri, Dec 2, 2011 at 8:56 PM, Alexander Repenning
<ralex at cs.colorado.edu> wrote:
> Using Mark Kantrowitz old but very handy infix we noticed some peculiar
> pattern of errors where very basic expressions do not correctly convert
> infix expressions into prefix ones. The version I just tried was this
> one: http://www.cliki.net/infix
>
> in => pre, red for incorrect
>
> "a + 1"   => (+ A 1)
> "s + 1"   =>  S+1
> "s - 1"   =>  S-1
> "s * 1" => (* S 1)
> "a + 1.5"  => (+ A 1.5)
> "s + 1.5"  => (+ S 1.5)
> "s + s" => (+ S S)
> "s + 1 + 1" => (+ S+1 1)
> "s + 1e1" => (+ S 10.0)
>
> Can somebody see a pattern here? AFAIK, the combination of the one letter
> variables names that are characters D, E, F, L, or S followed by "+" or "-"
> and then followed by an int does not work.

Didn't look into the code, but those letters are special…

CL-USER 15 > (list 1.0d+0 1.0d-0
                   1.0e+10 1.0e-10
                   1.0f+0 1.0f-0
                   1.0l+0 1.0f-0
                   1.0s+0 1.0s-0)
(1.0D0 1.0D0 1.0E10 1.0E-10 1.0 1.0 1.0D0 1.0 1.0S0 1.0S0)

//JT

-- 
Joshua Taylor, http://www.cs.rpi.edu/~tayloj/



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