Hi,
I have put the power operator onto my long-term TODO list (aka
README-4-compliance), SVN 402.
BTW the somewhat unexpected behavior of your niladic functions comes
from the IMHO broken syntax
of the rank operator (which allows values where unaware people would
expect functions). Before that
your right lambda would have returned a value and the SEL would have
triggered a syntax error.
My concern in the context of lambdas is that if we drive that too far
then we would create new cases
that nobody can understand anymore.
/// Jürgen
On 07/29/2014 02:11 PM, Elias Mårtenson wrote:
Hmm, so having a right-hand nildaic function passed to an operator
simply doesn't work. Oh well, makes sense once you think about it. :-)
This was all part of experimentation I was playing around with while
thinking about the power operator. Have you given that one any thought
yet?
Regards,
Elias
On 29 July 2014 19:55, Juergen Sauermann
<juergen.sauerm...@t-online.de <mailto:juergen.sauerm...@t-online.de>>
wrote:
Hi Elias,
this is because your lambdas are niladic. The right lambda is
called before SEL,
while the left lambda is called by SEL. From SEL's perspective,
'then'; is a function
while 'else' is a value.
/// Jürgen
On 07/29/2014 07:21 AM, Elias Mårtenson wrote:
I was writing an operator that acts as an "if"-statement, calling
one of two functions depending on the value of the argument:
∇Z ← (then SEL else) arg
→(arg=1)/do¯then
→(arg=0)/do¯else
⎕ES 'Illegal value for arg'
→0
do¯then:
Z ← then arg
→0
do¯else:
Z ← else arg
∇
Note that the then and else functions are called with an argument
"arg". When I call this operator with two nihilic lambda
functions, I get very strange behaviour:
* ⊣ ({⎕←'was true'} SEL {⎕←'was false'}) 0*
was false
* ⊣ ({⎕←'was true'} SEL {⎕←'was false'}) 1*
was false
was true
I would expect to get an error message here, or perhaps seeing
(⎕NC '⍵') to be 0. I certainly didn't expect to see both
functions be called. My suspicion is that there is a problem with
the parser somewhere, but I think Jürgen will have to look at
this one.
Regards,
Elias
