Using generators in Icon
Using generators in Icon |
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The Icon expression ``1 to 5'' is a simple example of
a generator expression, that is, one that produces more than
one result.
You can write procedures that act as generators. In this example, Two_Powers is a procedure that takes two arguments a and b and generates the sequence of powers of two, from 2 to the a power to 2 to the b power:
procedure Two_Powers ( a, b )
#--Generates 2^a, 2^(a+1), ..., 2^b
local i
every i := a to b do # Let i = a, a+1, a+2, ..., b
suspend 2^i; # Each time, return 2^i
fail; # No more results; fail
end
The statement ``suspend e1'' means
``return e1 as the next value of this procedure.''
The fail statement means ``there are no more
values to return.''