37 lines
981 B
Text
37 lines
981 B
Text
# Loops
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RETRO provides several words for creating loops.
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## Unconditional Loops
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An unconditional loop begins with `repeat` and ends with `again`.
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:test repeat #1 n:put sp again ;
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test
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Unconditional loops must be inside a definition or quote. To exit
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one of these, use `0;`, `-if;` or `if;`.
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:test #100 repeat 0; dup n:put sp n:dec again ;
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test
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:test #100 repeat dup #50 eq? [ 'done! s:put nl ] if; n:dec again ;
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test
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## Counted Loops
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There are two combinators for counted loops. These are `times` and
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`times<with-index>`.
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#0 #10 [ dup n:put sp n:inc ] times nl
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#10 [ I n:put sp ] times<with-index>
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The `times<with-index>` provides an index via the `I`, `J`, and
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`K` words. `I` will be the index of the current loop, with `J` and
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`K` being the indexes of the next two older loops.
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The loop indexes can be accessed outside the loop body:
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:display I n:square n:put sp ;
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:squares [ display ] times<with-index> nl ;
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#100 squares
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