51 lines
1008 B
Markdown
51 lines
1008 B
Markdown
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# Iterators
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Tomo supports using functions as iterable objects. This allows you to write
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arbitrary iteration behavior, such as using a polling-based API, and write
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regular loops or comprehensions over that API.
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For example, the `Path.each_line()` API method returns a function that
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successively gets one line from a file at a time until the file is exhausted:
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```tomo
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(./test.txt):write("
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line one
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line two
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line three
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")
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>> iter := (./test.txt):each_line()
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>> iter()
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= "line one"?
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>> iter()
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= "line two"?
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>> iter()
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= "line three"?
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>> iter()
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= !Text
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for line in (./test.txt):each_line():
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pass
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```
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You can write your own iterator methods this way. For example, this iterator
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iterates over prime numbers up to a given limit:
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```tomo
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func primes_up_to(limit:Int):
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n := 2
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return func():
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if n > limit:
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return !Int
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while not n:is_prime():
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n += 1
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n += 1
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return (n - 1)?
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>> [p for p in primes_up_to(11)]
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= [2, 3, 5, 7, 11]
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```
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