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Move some doc text around.

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Graydon Hoare 2012-01-19 18:29:34 -08:00
parent 59ebe6af18
commit 6ffc36bb1b
1 changed files with 18 additions and 23 deletions
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doc/rust.md
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@ -1290,24 +1290,6 @@ Rust has two kinds of statement:
[declaration statements](#declaration-statements) and [declaration statements](#declaration-statements) and
[expression statements](#expression-statements). [expression statements](#expression-statements).
A declaration serves to introduce a *name* that can be used in the block
*scope* enclosing the statement: all statements before and after the
name, from the previous opening curly-brace (`{`) up to the next closing
curly-brace (`}`).
An expression plays the dual roles of causing side effects and producing a
*value*. Expressions are said to *evaluate to* a value, and the side effects
are caused during *evaluation*. Many expressions contain sub-expressions as
operands; the definition of each kind of expression dictates whether or not,
and in which order, it will evaluate its sub-expressions, and how the
expression's value derives from the value of its sub-expressions.
In this way, the structure of execution -- both the overall sequence of
observable side effects and the final produced value -- is dictated by the
structure of expressions. Blocks themselves are expressions, so the nesting
sequence of block, statement, expression, and block can repeatedly nest to an
arbitrary depth.
### Declaration statements ### Declaration statements
A _declaration statement_ is one that introduces a *name* into the enclosing A _declaration statement_ is one that introduces a *name* into the enclosing
@ -1363,6 +1345,19 @@ the side effects of the expression's evaluation.
## Expressions ## Expressions
An expression plays the dual roles of causing side effects and producing a
*value*. Expressions are said to *evaluate to* a value, and the side effects
are caused during *evaluation*. Many expressions contain sub-expressions as
operands; the definition of each kind of expression dictates whether or not,
and in which order, it will evaluate its sub-expressions, and how the
expression's value derives from the value of its sub-expressions.
In this way, the structure of execution -- both the overall sequence of
observable side effects and the final produced value -- is dictated by the
structure of expressions. Blocks themselves are expressions, so the nesting
sequence of block, statement, expression, and block can repeatedly nest to an
arbitrary depth.
### Literal expressions ### Literal expressions
A _literal expression_ consists of one of the [literal](#literals) A _literal expression_ consists of one of the [literal](#literals)
@ -1759,7 +1754,7 @@ let x = ~10;
let y = [move x]; let y = [move x];
~~~~ ~~~~
Any access to `y` after applying the `move` operator to it is invalid, Any access to `x` after applying the `move` operator to it is invalid,
since it is no longer initialized at that point. since it is no longer initialized at that point.
### Call expressions ### Call expressions
@ -1770,10 +1765,10 @@ paren_expr_list : '(' expr_list ')' ;
call_expr : expr paren_expr_list ; call_expr : expr paren_expr_list ;
~~~~~~~~ ~~~~~~~~
A _call expression_ invokes a function, providing a tuple of input slots A _call expression_ invokes a function, providing zero or more input slots and
and a reference slot to serve as the function's output, bound to the an optional reference slot to serve as the function's output, bound to the
`lval` on the right hand side of the call. If the function eventually `lval` on the right hand side of the call. If the function eventually returns,
returns, then the expression completes. then the expression completes.
A call expression statically requires that the precondition declared in the A call expression statically requires that the precondition declared in the
callee's signature is satisfied by the expression prestate. In this way, callee's signature is satisfied by the expression prestate. In this way,