37 lines
820 B
Text
37 lines
820 B
Text
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# this function returns an iterator when called
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fn count_by(delta, limit) {
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let counter = 0;
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return fn() {
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if counter >= limit {
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return nil;
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}
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let prev_value = counter;
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counter += delta;
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return prev_value;
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};
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}
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# counter is an iterator
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# iterators are functions that:
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# - take no arguments
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# - return nil once done
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# - once returned nil once, must do so for all subsequent calls
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# the interpreter only checks the first requirement
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let counter = count_by(2, 5);
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println(counter()); # 0
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println(counter()); # 2
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println(counter()); # 4
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# println(counter()); # nil
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# println(counter()); # nil
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println("counting by 3s up to 20:");
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for n: count_by(3, 20) {
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println(n);
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}
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println("counting by 7s up to 40:");
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for n: count_by(7, 40) {
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println(n);
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}
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