caller. Every control path in a diverging function must end with a `panic!()` or
a call to another diverging function on every control path. The `!` annotation
does *not* denote a type. Rather, the result type of a diverging function is a
-special type called $\bot$ ("bottom") that unifies with any type. Rust has no
-syntax for $\bot$.
+special type called ⊥ ("bottom") that unifies with any type. Rust has no
+syntax for ⊥.
It might be necessary to declare a diverging function because as mentioned
previously, the typechecker checks that every control path in a function ends
trait Seq<T> {
fn len(&self) -> uint;
fn elt_at(&self, n: uint) -> T;
- fn iter(&self, |T|);
+ fn iter<F>(&self, F) where F: Fn(T);
}
```
function argument, and call it with a lambda expression as an argument.
```
-fn ten_times(f: |int|) {
+fn ten_times<F>(f: F) where F: Fn(int) {
let mut i = 0;
while i < 10 {
f(i);
```
-Patterns can also dereference pointers by using the `&`, `box` symbols,
-as appropriate. For example, these two matches on `x: &int` are equivalent:
+Patterns can also dereference pointers by using the `&`, `&mut` and `box`
+symbols, as appropriate. For example, these two matches on `x: &int` are
+equivalent:
```
# let x = &3i;
let mut x = add(5,7);
-type Binop<'a> = |int,int|: 'a -> int;
+type Binop = fn(int, int) -> int;
let bo: Binop = add;
x = bo(5,7);
```
```rust
let captured_var = 10i;
-let closure_no_args = || println!("captured_var={}", captured_var);
+let closure_no_args = |&:| println!("captured_var={}", captured_var);
-let closure_args = |arg: int| -> int {
+let closure_args = |&: arg: int| -> int {
println!("captured_var={}, arg={}", captured_var, arg);
arg // Note lack of semicolon after 'arg'
};
-fn call_closure(c1: ||, c2: |int| -> int) {
+fn call_closure<F: Fn(), G: Fn(int) -> int>(c1: F, c2: G) {
c1();
c2(2);
}
*TODO*.
-# Appendix: Influences and further references
-
-## Influences
-
-> The essential problem that must be solved in making a fault-tolerant
-> software system is therefore that of fault-isolation. Different programmers
-> will write different modules, some modules will be correct, others will have
-> errors. We do not want the errors in one module to adversely affect the
-> behaviour of a module which does not have any errors.
->
-> — Joe Armstrong
-
-> In our approach, all data is private to some process, and processes can
-> only communicate through communications channels. *Security*, as used
-> in this paper, is the property which guarantees that processes in a system
-> cannot affect each other except by explicit communication.
->
-> When security is absent, nothing which can be proven about a single module
-> in isolation can be guaranteed to hold when that module is embedded in a
-> system [...]
->
-> — Robert Strom and Shaula Yemini
-
-> Concurrent and applicative programming complement each other. The
-> ability to send messages on channels provides I/O without side effects,
-> while the avoidance of shared data helps keep concurrent processes from
-> colliding.
->
-> — Rob Pike
-
-Rust is not a particularly original language. It may however appear unusual by
-contemporary standards, as its design elements are drawn from a number of
-"historical" languages that have, with a few exceptions, fallen out of favour.
-Five prominent lineages contribute the most, though their influences have come
-and gone during the course of Rust's development:
-
-* The NIL (1981) and Hermes (1990) family. These languages were developed by
- Robert Strom, Shaula Yemini, David Bacon and others in their group at IBM
- Watson Research Center (Yorktown Heights, NY, USA).
-
-* The Erlang (1987) language, developed by Joe Armstrong, Robert Virding, Claes
- Wikström, Mike Williams and others in their group at the Ericsson Computer
- Science Laboratory (Älvsjö, Stockholm, Sweden) .
-
-* The Sather (1990) language, developed by Stephen Omohundro, Chu-Cheow Lim,
- Heinz Schmidt and others in their group at The International Computer
- Science Institute of the University of California, Berkeley (Berkeley, CA,
- USA).
-
-* The Newsqueak (1988), Alef (1995), and Limbo (1996) family. These
- languages were developed by Rob Pike, Phil Winterbottom, Sean Dorward and
- others in their group at Bell Labs Computing Sciences Research Center
- (Murray Hill, NJ, USA).
-
-* The Napier (1985) and Napier88 (1988) family. These languages were
- developed by Malcolm Atkinson, Ron Morrison and others in their group at
- the University of St. Andrews (St. Andrews, Fife, UK).
-
-Additional specific influences can be seen from the following languages:
-
-* The structural algebraic types and compilation manager of SML.
-* The attribute and assembly systems of C#.
-* The references and deterministic destructor system of C++.
-* The memory region systems of the ML Kit and Cyclone.
-* The typeclass system of Haskell.
-* The lexical identifier rule of Python.
-* The block syntax of Ruby.
+# Appendix: Influences
+
+Rust is not a particularly original language, with design elements coming from
+a wide range of sources. Some of these are listed below (including elements
+that have since been removed):
+
+* SML, OCaml: algebraic datatypes, pattern matching, type inference,
+ semicolon statement separation
+* C++: references, RAII, smart pointers, move semantics, monomorphisation,
+ memory model
+* ML Kit, Cyclone: region based memory management
+* Haskell (GHC): typeclasses, type families
+* Newsqueak, Alef, Limbo: channels, concurrency
+* Erlang: message passing, task failure, ~~linked task failure~~,
+ ~~lightweight concurrency~~
+* Swift: optional bindings
+* Scheme: hygienic macros
+* C#: attributes
+* Ruby: ~~block syntax~~
+* NIL, Hermes: ~~typestate~~
+* [Unicode Annex #31](http://www.unicode.org/reports/tr31/): identifier and
+ pattern syntax
[ffi]: guide-ffi.html
[plugin]: guide-plugin.html
projects / rust.git / blobdiff