Mapcar shortcoming or my knownledge deficiency?

[Ahankhah]

Hi,

as most of you know, the syntax of mapcad function is as following:

 

(mapcar [i]function [/i][i]list1[/i]... [i]listn[/i])

 

My question can be explained after showing these two examples:

 

(mapcar 'strcase '("a" "B" "c" "D"))
returns: ("A" "B" "C" "D")

 

(mapcar 'strcase '("a" "B" "c" "D") '(T T T T))
returns: ("a" "b" "c" "d")

 

Is any method to pass repeated objects (here T as the socond argument) to mapcar just one time?

[BlackBox]

Is any method to pass repeated objects (here T as the socond argument) to mapcar just one time?

 

*IF* you know you'll be using T (True) as the Which argument of the Strcase function for each item of the supplied list of valid strings, then the use of Lambda should do the trick.

 

Example:

 

(mapcar
 [color=blue](function[/color]
[color=blue]   (lambda (str / string)[/color]
[color=blue]     (setq string (strcase str [color=red]T[/color]))))[/color]
 '("a" "B" "c" "D"))

[Ahankhah]

Nice one RenderMan - much appreciated:).

[Ahankhah]

(mapcar
[color=blue](function[/color]
[color=blue](lambda (str / string)[/color]
[color=blue](setq string (strcase str [color=red]T[/color]))))[/color]
'("a" "B" "c" "D"))

the code can be even shorter:

 

(mapcar
 (function
  (lambda (str)
   (strcase str T)))
 '("a" "B" "c" "D"))

 

Thanks again RenderMan

[Lee Mac]

Mapcar is ideal when processing lists of unknown length; should you need to supply other constant arguments for each item, a lambda function (or user-defined subfunction) may be used, as demonstrated.

 

Perhaps have a read of this tutorial, the link at the bottom of that page is also a good read.

[BlackBox]

Nice one RenderMan - much appreciated:).

 

Your welcome.

[Ahankhah]

Thanks Lee,

you are very good teacher.