| Procedures in Nim are what we would call functions in other languages. | |
| As you've noticed in the previous examples, procedure is often abbreviated to proc. | |
Procedure can be declared with a proc statement.
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proc greet() =
echo "Greetings!"
greet()
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Here's a procedure that takes two arguments, a string and an int.
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proc greet(name: string, times: int) =
echo "Greeting ", name, " ", times, " times!"
greet("Bob", 2)
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| If procedure has parameters, parantheses when calling it are optional. |
greet "Bob", 3
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| When declaring consecutive procedure arguments of the same type, we can omit the argument type for all but last argument of the same type. |
proc greet(greeting, name: string, times: int) =
echo greeting, " ", name, " ", times, " times!"
greet("Hello", "Bob", 4)
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| Here's a procedure with a defined return type. |
proc sum1(a, b, c: int): int =
return a + b + c
echo sum1(3, 3, 4)
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Procs that declare return type have result variable available in-scope,
which, if used, is implicitly returned if there is no explicit return.
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proc sum2(a, b, c: int): int =
result = a + b
result = result + c
# will return result
echo sum2(10, 5, 5)
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If result variable is not used, the very last statement in the proc is returned.
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proc sum3(a, b, c: int): int =
discard a + b
echo "nothing"
b + c
# will return b + c
echo sum3(1, 10, 10)
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This also means return statement at the end of the proc can be omitted.
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proc sum4(a, b, c: int): int =
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Howver, return can still be useful for early returns.
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if a < 0:
return -a + b + c
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var my_sum = a + b + c
my_sum
# will return my_sum
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echo sum4(10, 10, 15)
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Another example without return statement.
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proc sum5(a, b, c: int): int = a + b + c
echo sum5(10, 10, 5)
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$ nim c -r procedures.nim Greetings! Greeting Bob 2 times! Greeting Bob 3 times! Hello Bob 4 times! 10 20 nothing 20 35 25 |
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Previously: Tables
Next up: Procedures (contd.)