Updated Nim for Python Programmers (markdown)
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Federico Ceratto
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@ -117,187 +117,4 @@ It is possible to implement object-orientation features from other languages (li
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### Structs - Tuples and Objects
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Tuples and Objects in Nim are kind of like structs in C, but not really.
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### Cheat Sheet
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WARNING: FIXME: this cheat sheet is for C, not Python.
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Note: Code examples are not exactly one-to-one, there may be subtle differences in the semantics. See comments.
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<table>
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<tr>
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<th>C</th><th>Nim</th><th>Comment</th>
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</tr>
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<tr>
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<td>
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<pre>
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int x;
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int y = 2;
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</pre>
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</td>
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<td>
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<pre>
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var x : int
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var y1 : int = 2
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var y2 = 2
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let z = 2
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</pre>
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</td>
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<td><b>Define variable</b>. y2 uses type inference. z is single-assignment. In Nim, uninitialized variables is initialized to 0/nil or similar defaults.</i>
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</td>
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</tr>
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<tr>
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<td>
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<pre>
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char s[] = "Hello World.";
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char s0 = s[0]; // 'H'
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char *t = s; // Ptr to s
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s[11] = '!';
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// s, t == "Hello World!"
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</pre>
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</td>
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<td>
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<pre>
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var s = "Hello World."
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var s0: char = s[0] # 'H'
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var t = s # Copy of s
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s[11] = '!'
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# s is "Hello World!"
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# t is "Hello World."
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</pre>
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</td>
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<td><b>Strings and char</b>. Strings are pass-by-value (copied on assignment) and strictly bounds-checked on access.</i>
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</td>
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</tr>
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<tr>
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<td>
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<pre>
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char a = '\n';
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printf("byte %d\nA%cB\n",
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a, a);
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</pre>
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</td>
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<td>
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<pre>
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let a = '\L'
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echo "byte ", $int(a),
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"\nA" & $a & "B"
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</pre>
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</td>
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<td><b>Newlines and chars</b>. In nim you can't use ``\n`` as a character literal, because on the Windows platform it expands to CR+LR. So you need to specify which char to use.</i>
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</td>
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</tr>
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<tr>
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<td>
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<pre>
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9 % 8 // 1
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-9 % 8 // -1
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(unsigned)(-9) %
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(unsigned)(8) // 7
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</pre>
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</td>
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<td>
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<pre>
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9 mod 8 # 1
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-9 mod 8 # -1
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-9 %% 8 # 7
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</pre>
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</td>
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<td><b>Modulo operator</b>. <i>%% treats its argument as unsigned numbers. <a href="http://nim-lang.org/manual.html#pre-defined-integer-types">See</a></i></i>
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</td>
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</tr>
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<tr>
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<td>
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<pre>
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int x = foobar() ? 42 : 0;
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</pre>
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</td>
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<td>
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<pre>
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var x = if foobar(): 42
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else: 0
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</pre>
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</td>
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<td>
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<i>If-statements return the value of the expression they evaluate to, so Nim doesn't need a </i><b>ternary operator</b>.</i>
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</td>
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</tr>
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<tr>
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<td>
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<pre>
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void foo() {
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printf("Hello World\n");
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}
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int bar() {
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return 2;
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}
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int baz(int x) {
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return x*2;
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}
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</pre>
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</td>
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<td>
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<pre>
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proc foo() =
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echo "Hello World"
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proc bar(): int =
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2
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proc baz(x: int) =
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x*2
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</pre>
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</td>
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<td><b>Function/Procedure.</b> </td>
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</tr>
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<tr>
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<td>
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<pre>
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int a = 3
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int *b = &a;
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</pre>
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</td>
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<td>
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<pre>
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var a = 3
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var b = addr(a)
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</pre>
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</td>
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<td><b>Getting an address.</b> <i></i> </td>
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</tr>
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<tr>
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<td>
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<pre>
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void foobar(person_t *a) {
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person_t b;
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b = *a;
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b.name = "Bob";
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*a = b;
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}
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</pre>
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</td>
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<td>
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<pre>
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proc foobar(a: ref TPerson) =
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var b: TPerson
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b = a[]
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b.name = "Bob"
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a[] = b
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</pre>
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</td>
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<td><b>Dereference.</b> <i>In C, only the pointer to the strings in the struct is copied. In Nim, the string is also copied, but refs are not deep-copied.</i> </td>
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</tr>
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</table>
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Tuples are entirely different from Python
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