nim-wiki/Nimrod-for-C-programmers.md

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(Work in progress)
This is a guide for people with experience in C or a similar language. The general tutorials can be found here:
http://nimrod-lang.org/tut1.html
http://nimrod-lang.org/tut2.html
The manual provides a more or less complete overview of the language:
http://nimrod-lang.org/manual.html
### Structs - Tuples and Objects
Tuples and Objects in Nimrod are kind of like structs in C, but not really.
### Interfacing C and Nimrod
See [Foreign Function Interface](http://nimrod-lang.org/manual.html#foreign-function-interface)
### Converting C code to Nimrod
See [c2nim](http://nimrod-lang.org/c2nim.html)
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### Cheat Sheet
Note: Code examples are not exactly one-to-one, there may be subtle differences in the semantics. See comments.
<table>
<tr>
<th>C</th><th>Nimrod</th><th>Comment</th>
</tr>
<tr>
<td>
```C
int x;
int y = 2;
```
</td>
<td>
```Nimrod
var x : int
var y1 : int = 2
var y2 = 2
let z = 2
```
</td>
<td><b>Define variable</b>. y2 uses type inference. z is single-assignment.</i>
</td>
</tr>
<tr>
<td>
```C
9 % 8 // 1
-9 % 8 // -1
(unsigned)(-9) % (unsigned)(8) // 7
```
</td>
<td>
```Nimrod
9 mod 8 # 1
-9 mod 8 # -1
-9 %% 8 # 7
```
</td>
<td><b>Modulo operator</b>. <i>%% treats its argument as unsigned numbers. <a href="http://nimrod-lang.org/manual.html#pre-defined-integer-types">See</a></i></i>
</td>
</tr>
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<tr>
<td>
```C
int x = foobar() ? 42 : 0;
```
</td>
<td>
```Nimrod
var x = if foobar(): 42 else: 0
```
</td>
<td>
<i>If-statements return the value of the expression they evaluate to, so Nimrod doesn't need a </i><b>ternary operator</b>.</i>
</td>
</tr>
<tr>
<td>
```C
void foo() {
printf("Hello World\n");
}
int bar() {
return 2;
}
int baz(int x) {
return x*2;
}
```
</td>
<td>
```Nimrod
proc foo() =
echo "Hello World"
proc bar() : int =
2
proc baz(x : int) =
x*2
```
</td>
<td><b>Function/Procedure.</b> </td>
</tr>
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<tr>
<td>
```C
void foobar(person_t *a) {
person_t b;
b = *a;
b.name = "Bob";
*a = b;
}
```
</td>
<td>
```Nimrod
proc foobar(a: ref TPerson) =
var b: TPerson
b = a[]
b.name = "Bob"
a[] = b
```
</td>
<td><b>Dereference.</b> <i>In C, only the pointer to the strings in the struct is copied. In Nimrod, the string is also copied, but refs are not deep-copied.</i> </td>
</tr>
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</table>