mirror of
https://github.com/adambard/learnxinyminutes-docs.git
synced 2024-11-29 22:12:07 +03:00
298 lines
9.7 KiB
Markdown
298 lines
9.7 KiB
Markdown
---
|
|
language: neat
|
|
contributors:
|
|
- ["Feep", "https://github.com/FeepingCreature"]
|
|
filename: LearnNeat.nt
|
|
---
|
|
|
|
Neat is basically a smaller version of D1 with some experimental syntax and a focus on terseness without losing the basic C-like syntax.
|
|
|
|
[Read more here.](https://github.com/FeepingCreature/fcc/wiki)
|
|
|
|
```c
|
|
// single line comments start with //
|
|
/*
|
|
multiline comments look like this
|
|
*/
|
|
/+
|
|
or this
|
|
/+ these can be nested too, same as D +/
|
|
+/
|
|
|
|
// Module name. This has to match the filename/directory.
|
|
module LearnNeat;
|
|
|
|
// Make names from another module visible in this one.
|
|
import std.file;
|
|
// You can import multiple things at once.
|
|
import std.math, std.util;
|
|
// You can even group up imports!
|
|
import std.(process, socket);
|
|
|
|
// Global functions!
|
|
void foo() { }
|
|
|
|
// Main function, same as in C.
|
|
// string[] == "array of strings".
|
|
// "string" is just an alias for char[],
|
|
void main(string[] args) {
|
|
// Call functions with "function expression".
|
|
writeln "Hello World";
|
|
// You can do it like in C too... if you really want.
|
|
writeln ("Hello World");
|
|
// Declare a variable with "type identifier"
|
|
string arg = ("Hello World");
|
|
writeln arg;
|
|
// (expression, expression) forms a tuple.
|
|
// There are no one-value tuples though.
|
|
// So you can always use () in the mathematical sense.
|
|
// (string) arg; <- is an error
|
|
|
|
/*
|
|
byte: 8 bit signed integer
|
|
char: 8 bit UTF-8 byte component.
|
|
short: 16 bit signed integer
|
|
int: 32 bit signed integer
|
|
long: 64 bit signed integer
|
|
|
|
float: 32 bit floating point
|
|
double: 64 bit floating point
|
|
real: biggest native size floating point (80 bit on x86).
|
|
|
|
bool: true or false
|
|
*/
|
|
int a = 5;
|
|
bool b = true;
|
|
// as in C, && and || are short-circuit evaluating.
|
|
b = b && false;
|
|
assert(b == false);
|
|
// "" are "format strings". So $variable will be substituted at runtime
|
|
// with a formatted version of the variable.
|
|
writeln "$a";
|
|
// This will just print $a.
|
|
writeln `$a`;
|
|
// you can format expressions with $()
|
|
writeln "$(2+2)";
|
|
// Note: there is no special syntax for characters.
|
|
char c = "a";
|
|
// Cast values by using type: expression.
|
|
// There are three kinds of casts:
|
|
// casts that just specify conversions that would be happening automatically
|
|
// (implicit casts)
|
|
float f = float:5;
|
|
float f2 = 5; // would also work
|
|
// casts that require throwing away information or complicated computation -
|
|
// those must always be done explicitly
|
|
// (conversion casts)
|
|
int i = int:f;
|
|
// int i = f; // would not work!
|
|
// and, as a last attempt, casts that just reinterpret the raw data.
|
|
// Those only work if the types have the same size.
|
|
string s = "Hello World";
|
|
// Arrays are (length, pointer) pairs.
|
|
// This is a tuple type. Tuple types are (type, type, type).
|
|
// The type of a tuple expression is a tuple type. (duh)
|
|
(int, char*) array = (int, char*): s;
|
|
// You can index arrays and tuples using the expression[index] syntax.
|
|
writeln "pointer is $(array[1]) and length is $(array[0])";
|
|
// You can slice them using the expression[from .. to] syntax.
|
|
// Slicing an array makes another array.
|
|
writeln "$(s[0..5]) World";
|
|
// Alias name = expression gives the expression a name.
|
|
// As opposed to a variable, aliases do not have an address
|
|
// and can not be assigned to. (Unless the expression is assignable)
|
|
alias range = 0 .. 5;
|
|
writeln "$(s[range]) World";
|
|
// You can iterate over ranges.
|
|
for int i <- range {
|
|
write "$(s[i])";
|
|
}
|
|
writeln " World";
|
|
// Note that if "range" had been a variable, it would be 'empty' now!
|
|
// Range variables can only be iterated once.
|
|
// The syntax for iteration is "expression <- iterable".
|
|
// Lots of things are iterable.
|
|
for char c <- "Hello" { write "$c"; }
|
|
writeln " World";
|
|
// For loops are "for test statement";
|
|
alias test = char d <- "Hello";
|
|
for test write "$d";
|
|
writeln " World\t\x05"; // note: escapes work
|
|
// Pointers: function the same as in C, btw. The usual.
|
|
// Do note: the pointer star sticks with the TYPE, not the VARIABLE!
|
|
string* p;
|
|
assert(p == null); // default initializer
|
|
p = &s;
|
|
writeln "$(*p)";
|
|
// Math operators are (almost) standard.
|
|
int x = 2 + 3 * 4 << 5;
|
|
// Note: XOR is "xor". ^ is reserved for exponentiation (once I implement that).
|
|
int y = 3 xor 5;
|
|
int z = 5;
|
|
assert(z++ == 5);
|
|
assert(++z == 7);
|
|
writeln "x $x y $y z $z";
|
|
// As in D, ~ concatenates.
|
|
string hewo = "Hello " ~ "World";
|
|
// == tests for equality, "is" tests for identity.
|
|
assert (hewo == s);
|
|
assert !(hewo is s);
|
|
// same as
|
|
assert (hewo !is s);
|
|
|
|
// Allocate arrays using "new array length"
|
|
int[] integers = new int[] 10;
|
|
assert(integers.length == 10);
|
|
assert(integers[0] == 0); // zero is default initializer
|
|
integers = integers ~ 5; // This allocates a new array!
|
|
assert(integers.length == 11);
|
|
|
|
// This is an appender array.
|
|
// Instead of (length, pointer), it tracks (capacity, length, pointer).
|
|
// When you append to it, it will use the free capacity if it can.
|
|
// If it runs out of space, it reallocates - but it will free the old array automatically.
|
|
// This makes it convenient for building arrays.
|
|
int[auto~] appender;
|
|
appender ~= 2;
|
|
appender ~= 3;
|
|
appender.free(); // same as {mem.free(appender.ptr); appender = null;}
|
|
|
|
// Scope variables are automatically freed at the end of the current scope.
|
|
scope int[auto~] someOtherAppender;
|
|
// This is the same as:
|
|
int[auto~] someOtherAppender2;
|
|
onExit { someOtherAppender2.free; }
|
|
|
|
// You can do a C for loop too
|
|
// - but why would you want to?
|
|
for (int i = 0; i < 5; ++i) { }
|
|
// Otherwise, for and while are the same.
|
|
while int i <- 0..4 {
|
|
assert(i == 0);
|
|
break; // continue works too
|
|
} then assert(false); // if we hadn't break'd, this would run at the end
|
|
// This is the height of loopdom - the produce-test-consume loop.
|
|
do {
|
|
int i = 5;
|
|
} while (i == 5) {
|
|
assert(i == 5);
|
|
break; // otherwise we'd go back up to do {
|
|
}
|
|
|
|
// This is a nested function.
|
|
// Nested functions can access the surrounding function.
|
|
string returnS() { return s; }
|
|
writeln returnS();
|
|
|
|
// Take the address of a function using &
|
|
// The type of a global function is ReturnType function(ParameterTypeTuple).
|
|
void function() foop = &foo;
|
|
|
|
// Similarly, the type of a nested function is ReturnType delegate(ParameterTypeTuple).
|
|
string delegate() returnSp = &returnS;
|
|
writeln returnSp();
|
|
// Class member functions and struct member functions also fit into delegate variables.
|
|
// In general, delegates are functions that carry an additional context pointer.
|
|
// ("fat pointers" in C)
|
|
|
|
// Allocate a "snapshot" with "new delegate".
|
|
// Snapshots are not closures! I used to call them closures too,
|
|
// but then my Haskell-using friends yelled at me so I had to stop.
|
|
// The difference is that snapshots "capture" their surrounding context
|
|
// when "new" is used.
|
|
// This allows things like this
|
|
int delegate(int) add(int a) {
|
|
int add_a(int b) { return a + b; }
|
|
// This does not work - the context of add_a becomes invalid
|
|
// when add returns.
|
|
// return &add_a;
|
|
// Instead:
|
|
return new &add_a;
|
|
}
|
|
int delegate(int) dg = add 2;
|
|
assert (dg(3) == 5);
|
|
// or
|
|
assert (((add 2) 3) == 5);
|
|
// or
|
|
assert (add 2 3 == 5);
|
|
// add can also be written as
|
|
int delegate(int) add2(int a) {
|
|
// this is an implicit, nameless nested function.
|
|
return new λ(int b) { return a + b; }
|
|
}
|
|
// or even
|
|
auto add3(int a) { return new λ(int b) -> a + b; }
|
|
// hahahaaa
|
|
auto add4 = λ(int a) -> new λ(int b) -> a + b;
|
|
assert(add4 2 3 == 5);
|
|
// If your keyboard doesn't have a λ (you poor sod)
|
|
// you can use \ too.
|
|
auto add5 = \(int a) -> new \(int b) -> a + b;
|
|
// Note!
|
|
auto nestfun = λ() { } // There is NO semicolon needed here!
|
|
// "}" can always substitute for "};".
|
|
// This provides syntactic consistency with built-in statements.
|
|
|
|
|
|
// This is a class.
|
|
// Note: almost all elements of Neat can be used on the module level
|
|
// or just as well inside a function.
|
|
class C {
|
|
int a;
|
|
void writeA() { writeln "$a"; }
|
|
// It's a nested class - it exists in the context of main().
|
|
// so if you leave main(), any instances of C become invalid.
|
|
void writeS() { writeln "$s"; }
|
|
}
|
|
C cc = new C;
|
|
// cc is a *reference* to C. Classes are always references.
|
|
cc.a = 5; // Always used for property access.
|
|
auto ccp = &cc;
|
|
(*ccp).a = 6;
|
|
// or just
|
|
ccp.a = 7;
|
|
cc.writeA();
|
|
cc.writeS(); // to prove I'm not making things up
|
|
// Interfaces work same as in D, basically. Or Java.
|
|
interface E { void doE(); }
|
|
// Inheritance works same as in D, basically. Or Java.
|
|
class D : C, E {
|
|
override void writeA() { writeln "hahahahaha no"; }
|
|
override void doE() { writeln "eeeee"; }
|
|
// all classes inherit from Object. (toString is defined in Object)
|
|
override string toString() { return "I am a D"; }
|
|
}
|
|
C cd = new D;
|
|
// all methods are always virtual.
|
|
cd.writeA();
|
|
E e = E:cd; // dynamic class cast!
|
|
e.doE();
|
|
writeln "$e"; // all interfaces convert to Object implicitly.
|
|
|
|
// Templates!
|
|
// Templates are parameterized namespaces, taking a type as a parameter.
|
|
template Templ(T) {
|
|
alias hi = 5, hii = 8;
|
|
// Templates always have to include something with the same name as the template
|
|
// - this will become the template's _value_.
|
|
// Static ifs are evaluated statically, at compile-time.
|
|
// Because of this, the test has to be a constant expression,
|
|
// or something that can be optimized to a constant.
|
|
static if (types-equal (T, int)) {
|
|
alias Templ = hi;
|
|
} else {
|
|
alias Templ = hii;
|
|
}
|
|
}
|
|
assert(Templ!int == 5);
|
|
assert(Templ!float == 8);
|
|
}
|
|
```
|
|
|
|
## Topics Not Covered
|
|
|
|
* Extended iterator types and expressions
|
|
* Standard library
|
|
* Conditions (error handling)
|
|
* Macros
|