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66 lines
2.0 KiB
Markdown
66 lines
2.0 KiB
Markdown
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# Control statements
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Control statements are used to control program flow. Using logical expressions, different branches of code will be run.
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## if statements
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The syntax for if statements in cosmo looks like:
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```
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if 1 == 1 then
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// true branch here
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print("true")
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else
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// false branch here
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print("false")
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end
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```
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> true
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the `elseif` keyword can also be used to have an else conditional branch:
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```
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if false then
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print("bye")
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elseif true then
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print("hi")
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end
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```
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> hi
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## while loops
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While loops are basic "repeat while X is true" loops. Their syntax consists of the `while` keyword, followed by the logical expression and the `do` keyword. The loop body is ended by the matching `end` keyword. In practice this looks like:
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```
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while true do
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print("oh no! infinite loop!")
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end
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```
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> oh no! infinite loop!oh no! infinite loop!oh no! infinite loop!...
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## for loops
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There are two main types of for loops, the traditional c-style for loops, and the for-each loop which requires an iterator object (see `objects.md`)
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The c-style for loops starts with the `for` keyword, followed by '(' and an initializer, a conditional expression, and an iterator statement each separated by a ';', followed by ')' then the `do` keyword. The loop body is ended by the matching `end` keyword. Like so:
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```
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var total = 0
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for (var i = 0; i < 10; i++) do
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total = total + i
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end
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print(total)
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```
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> 45
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The for-each loops are a little different, the absence of the starting '(' marks it as a for-each loop. After the `for` keyword, the values expected during iteration are expected, each separated by a ','. After that, the `in` keyword is expected and the iterator object is expected. The loop body is ended by the matching `end` keyword. The start of the loop body is marked by the `do` keyword. Like so:
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```
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for key, val in ["hello", "world"] do
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print("[" .. key .. "] = " .. val)
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end
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```
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> `[0] = hello [1] = world`
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Tables have a built-in iterator in the VM and are accepted in for-each loops. However, iterations over tables are not guaranteed to be in any specific order.
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