> ....
> In scheme, I believe you just have recursion.
> ....
Cousin TJR ....
I'm a total scheme rookie starting only about 3 days ago
and one of the mechanisms I went looking for was a technique
for iteration ....
Found in the scheme docs about iteration supplied
via the reduce package ....
"Iterate and reduce are extensions of named-let
for writing loops that walk down one or more sequences
such as the elements of a list or vector, the characters
read from a port, or arithmetic series .... "
The following scheme session illustrates a trivial example ....
> , open reduce
>
> ( define ( list_loop this_list )
( iterate loop
( ( list* this_item this_list ) ) ; iterate expression
( ( new_list '( ) ) ) ; state expression
( loop ( cons ( * 2 this_item ) new_list ) ) ; body expression
( reverse new_list ) ) ) ; final expression
; no values returned
>
> ( define L '( 1 2 3 4 5 ) )
; no values returned
>
( define result_i ( list_loop L ) )
; no values returned
>
> result_i
'(2 4 6 8 10)
>
However, just as in Python the map function
might be both easier to code and more readable
in many cases ....
> ( define ( x2 n ) ( * 2 n ) )
; no values returned
>
> ( define result_m ( map x2 L ) )
; no values returned
>
> result_m
'(2 4 6 8 10)
Note ....
No lambdas in my scheme code either .... ;-)
--
Stanley C. Kitching
Human Being
Phoenix, Arizona
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