Re: lambda... again

On Oct 23, 6:48 am, yuriy.ers...@xxxxxxxxx wrote:
Yes, I have read about ithttp://wiki.tcl.tk/519http://wiki.tcl.tk/10782

Why didn't anyone use this obvious variant?

proc lambda {p b} {
set name [list lambda $p $b]
if {[info procs $name] eq ""} {
proc $name $p $b
}
return $name

}

General lambda use cases work well:

% [lambda {s1 s2} {puts "s1=$s1 s2=$s2"}] asd cvb
s1=asd s2=cvb

% set aaa [lambda {s1 s2} {puts "s1=$s1 s2=$s2"}]
lambda {s1 s2} {puts "s1=$s1 s2=$s2"}
% $aaa q w
s1=q s2=w


Personally I think the [apply] method that we now have in 8.5 is the
way to go. Lambdas are after all merely values. So there is no reason
to treat a lambda as anything other than a string until you want to
use it as a function. So:

# In tcl a lambda is simply a string:
set aaa {{s1 s2} {puts "s1=$s1 s2=$s2"}}

# Only when you want to use it does it need special treatment:
apply $aaa q w

The advantage is that unlike the proc work-arounds the apply method
has all the advantages of regular variables: local scope, passable as
first class citizens etc.

The disadvantage is that calling a lambda is different from calling a
regular proc (you need to prepend apply to it). Now... if someone
feels like modifying [unknown] so that lambdas can be called like a
proc..... ;-)

.

Relevant Pages

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