Re: [q-lang-users] "listof" surprises

[Marco M. <ma...@ma...>]

On May 16, 2007, at 2:25 AM, Albert Graef wrote:

> ma...@ma... wrote:
>> I just got burned by this unexpected (for me, of course) behavior of
>> list comprehension.  Given the program
>>
>>    delta X X      = 1;
>>    delta _ _      = 0 otherwise;
>>    tabulate N M F = [[F I J : I in [1..N]] : J in [1..M]];
>>    eye N          = tabulate N N delta;
>>
>> then (eye 2) evaluates to [[0,0],[0,0]] instead of [[1,0],[0,1]] as I
>> would have imagined.
>
> Ok, this bug is fixed in cvs now (qmfuns.c revision 1.62).
>
> ==> eye 2
> [[1,0],[0,1]]

Thanks.

Unfortunately, I found another obstacle (bug?).
I really do not understand this: given the program

   special expr E;
   f (expr X) = expr X;
   g (expr 0) = expr 0;
   g (expr X) = expr X;

I get

   ==> f (expr random)
   expr random

   ==> g (expr random)
   expr 2635609360

M.