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basic declarations and definitions chapter converted, needs

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  1. +614 −697 06-basic-declarations-and-definitions.md
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1,311 06-basic-declarations-and-definitions.md
@@ -2,26 +2,26 @@ Basic Declarations and Definitions
==================================
-\syntax\begin{lstlisting}
- Dcl ::= `val' ValDcl
- | `var' VarDcl
- | `def' FunDcl
- | `type' {nl} TypeDcl
- PatVarDef ::= `val' PatDef
- | `var' VarDef
- Def ::= PatVarDef
- | `def' FunDef
- | `type' {nl} TypeDef
- | TmplDef
-\end{lstlisting}
-
-A {\em declaration} introduces names and assigns them types. It can
-form part of a class definition (\sref{sec:templates}) or of a
-refinement in a compound type (\sref{sec:refinements}).
-
-A {\em definition} introduces names that denote terms or types. It can
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.grammar}
+Dcl ::= val ValDcl
+ | var VarDcl
+ | def FunDcl
+ | type {nl} TypeDcl
+PatVarDef ::= val PatDef
+ | var VarDef
+Def ::= PatVarDef
+ | def FunDef
+ | type {nl} TypeDef
+ | TmplDef
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A _declaration_ introduces names and assigns them types. It can
+form part of a [class definition](#templates) or of a
+refinement in a [compound type](#compound-types).
+
+A _definition_ introduces names that denote terms or types. It can
form part of an object or class definition or it can be local to a
-block. Both declarations and definitions produce {\em bindings} that
+block. Both declarations and definitions produce _bindings_ that
associate type names with type definitions or bounds, and that
associate term names with types.
@@ -31,388 +31,331 @@ restriction on forward references in blocks: In a statement sequence
$s_1 \ldots s_n$ making up a block, if a simple name in $s_i$ refers
to an entity defined by $s_j$ where $j \geq i$, then for all $s_k$
between and including $s_i$ and $s_j$,
-\begin{itemize}
-\item $s_k$ cannot be a variable definition.
-\item If $s_k$ is a value definition, it must be lazy.
-\end{itemize}
-\comment{
-Every basic definition may introduce several defined names, separated
-by commas. These are expanded according to the following scheme:
-\bda{lcl}
-\VAL;x, y: T = e && \VAL; x: T = e \\
- && \VAL; y: T = x \\[0.5em]
-
-\LET;x, y: T = e && \LET; x: T = e \\
- && \VAL; y: T = x \\[0.5em]
-
-\DEF;x, y (ps): T = e &\tab\mbox{expands to}\tab& \DEF; x(ps): T = e \\
- && \DEF; y(ps): T = x(ps)\\[0.5em]
-
-\VAR;x, y: T := e && \VAR;x: T := e\\
- && \VAR;y: T := x\\[0.5em]
-
-\TYPE;t,u = T && \TYPE; t = T\\
- && \TYPE; u = t\\[0.5em]
-\eda
-
-All definitions have a ``repeated form'' where the initial
-definition keyword is followed by several constituent definitions
-which are separated by commas. A repeated definition is
-always interpreted as a sequence formed from the
-constituent definitions. E.g.\ the function definition
-~\lstinline@def f(x) = x, g(y) = y@~ expands to
-~\lstinline@def f(x) = x; def g(y) = y@~ and
-the type definition
-~\lstinline@type T, U <: B@~ expands to
-~\lstinline@type T; type U <: B@.
-}
-\comment{
-If an element in such a sequence introduces only the defined name,
-possibly with some type or value parameters, but leaves out any
-additional parts in the definition, then those parts are implicitly
-copied from the next subsequent sequence element which consists of
-more than just a defined name and parameters. Examples:
-\begin{itemize}
-\item[]
-The variable declaration ~\lstinline@var x, y: Int@~
-expands to ~\lstinline@var x: Int; var y: Int@.
-\item[]
-The value definition ~\lstinline@val x, y: Int = 1@~
-expands to ~\lstinline@val x: Int = 1; val y: Int = 1@.
-\item[]
-The class definition ~\lstinline@case class X(), Y(n: Int) extends Z@~ expands to
-~\lstinline@case class X extends Z; case class Y(n: Int) extends Z@.
-\item
-The object definition ~\lstinline@case object Red, Green, Blue extends Color@~
-expands to
-\begin{lstlisting}
-case object Red extends Color
-case object Green extends Color
-case object Blue extends Color .
-\end{lstlisting}
-\end{itemize}
-}
-\section{Value Declarations and Definitions}
-\label{sec:valdef}
-
-\syntax\begin{lstlisting}
- Dcl ::= `val' ValDcl
- ValDcl ::= ids `:' Type
- PatVarDef ::= `val' PatDef
- PatDef ::= Pattern2 {`,' Pattern2} [`:' Type] `=' Expr
- ids ::= id {`,' id}
-\end{lstlisting}
-
-A value declaration ~\lstinline@val $x$: $T$@~ introduces $x$ as a name of a value of
+- $s_k$ cannot be a variable definition.
+- If $s_k$ is a value definition, it must be lazy.
+
+
+Value Declarations and Definitions
+----------------------------------
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.grammar}
+Dcl ::= ‘val’ ValDcl
+ValDcl ::= ids ‘:’ Type
+PatVarDef ::= ‘val’ PatDef
+PatDef ::= Pattern2 {‘,’ Pattern2} [‘:’ Type] ‘=’ Expr
+ids ::= id {‘,’ id}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A value declaration `val $x$: $T$` introduces $x$ as a name of a value of
type $T$.
-A value definition ~\lstinline@val $x$: $T$ = $e$@~ defines $x$ as a
+A value definition `val $x$: $T$ = $e$` defines $x$ as a
name of the value that results from the evaluation of $e$.
If the value definition is not recursive, the type
-$T$ may be omitted, in which case the packed type (\sref{sec:expr-typing}) of expression $e$ is
-assumed. If a type $T$ is given, then $e$ is expected to conform to
-it.
+$T$ may be omitted, in which case the [packed type](#expression-typing) of
+expression $e$ is assumed. If a type $T$ is given, then $e$ is expected to
+conform to it.
Evaluation of the value definition implies evaluation of its
-right-hand side $e$, unless it has the modifier \lstinline@lazy@. The
+right-hand side $e$, unless it has the modifier `lazy`. The
effect of the value definition is to bind $x$ to the value of $e$
-converted to type $T$. A \lstinline@lazy@ value definition evaluates
+converted to type $T$. A `lazy` value definition evaluates
its right hand side $e$ the first time the value is accessed.
-A {\em constant value definition} is of the form
-\begin{lstlisting}
+A _constant value definition_ is of the form
+
+~~~~~~~~~~~~~~~~ {.scala}
final val x = e
-\end{lstlisting}
-where \lstinline@e@ is a constant expression
-(\sref{sec:constant-expression}).
-The \lstinline@final@ modifier must be
+~~~~~~~~~~~~~~~~
+
+where `e` is a [constant expression](#constant-expressions).
+The `final` modifier must be
present and no type annotation may be given. References to the
-constant value \lstinline@x@ are themselves treated as constant expressions; in the
-generated code they are replaced by the definition's right-hand side \lstinline@e@.
+constant value `x` are themselves treated as constant expressions; in the
+generated code they are replaced by the definition's right-hand side `e`.
-Value definitions can alternatively have a pattern
-(\sref{sec:patterns}) as left-hand side. If $p$ is some pattern other
+Value definitions can alternatively have a [pattern](#patterns)
+as left-hand side. If $p$ is some pattern other
than a simple name or a name followed by a colon and a type, then the
-value definition ~\lstinline@val $p$ = $e$@~ is expanded as follows:
+value definition `val $p$ = $e$` is expanded as follows:
-1. If the pattern $p$ has bound variables $x_1 \commadots x_n$, where $n > 1$:
-\begin{lstlisting}
-val $\Dollar x$ = $e$ match {case $p$ => {$x_1 \commadots x_n$}}
-val $x_1$ = $\Dollar x$._1
+1. If the pattern $p$ has bound variables $x_1 , \ldots , x_n$, where $n > 1$:
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+val $\$ x$ = $e$ match {case $p$ => {$x_1 , \ldots , x_n$}}
+val $x_1$ = $\$ x$._1
$\ldots$
-val $x_n$ = $\Dollar x$._n .
-\end{lstlisting}
-Here, $\Dollar x$ is a fresh name.
+val $x_n$ = $\$ x$._n .
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Here, $\$ x$ is a fresh name.
2. If $p$ has a unique bound variable $x$:
-\begin{lstlisting}
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
val $x$ = $e$ match { case $p$ => $x$ }
-\end{lstlisting}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3. If $p$ has no bound variables:
-\begin{lstlisting}
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
$e$ match { case $p$ => ()}
-\end{lstlisting}
-
-\example
-The following are examples of value definitions
-\begin{lstlisting}
-val pi = 3.1415
-val pi: Double = 3.1415 // equivalent to first definition
-val Some(x) = f() // a pattern definition
-val x :: xs = mylist // an infix pattern definition
-\end{lstlisting}
-
-The last two definitions have the following expansions.
-\begin{lstlisting}
-val x = f() match { case Some(x) => x }
-
-val x$\Dollar$ = mylist match { case x :: xs => {x, xs} }
-val x = x$\Dollar$._1
-val xs = x$\Dollar$._2
-\end{lstlisting}
-
-The name of any declared or defined value may not end in \lstinline@_=@.
-
-A value declaration ~\lstinline@val $x_1 \commadots x_n$: $T$@~
-is a
-shorthand for the sequence of value declarations
-~\lstinline@val $x_1$: $T$; ...; val $x_n$: $T$@.
-A value definition ~\lstinline@val $p_1 \commadots p_n$ = $e$@~
-is a
-shorthand for the sequence of value definitions
-~\lstinline@val $p_1$ = $e$; ...; val $p_n$ = $e$@.
-A value definition ~\lstinline@val $p_1 \commadots p_n: T$ = $e$@~
-is a
-shorthand for the sequence of value definitions
-~\lstinline@val $p_1: T$ = $e$; ...; val $p_n: T$ = $e$@.
-
-\section{Variable Declarations and Definitions}
-\label{sec:vardef}
-
-\syntax\begin{lstlisting}
- Dcl ::= `var' VarDcl
- PatVarDef ::= `var' VarDef
- VarDcl ::= ids `:' Type
- VarDef ::= PatDef
- | ids `:' Type `=' `_'
-\end{lstlisting}
-
-A variable declaration ~\lstinline@var $x$: $T$@~ is equivalent to declarations
-of a {\em getter function} $x$ and a {\em setter function}
-\lstinline@$x$_=@, defined as follows:
-
-\begin{lstlisting}
- def $x$: $T$
- def $x$_= ($y$: $T$): Unit
-\end{lstlisting}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+(@) The following are examples of value definitions
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ val pi = 3.1415
+ val pi: Double = 3.1415 // equivalent to first definition
+ val Some(x) = f() // a pattern definition
+ val x :: xs = mylist // an infix pattern definition
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ The last two definitions have the following expansions.
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ val x = f() match { case Some(x) => x }
+
+ val x$\$$ = mylist match { case x :: xs => {x, xs} }
+ val x = x$\$$._1
+ val xs = x$\$$._2
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+The name of any declared or defined value may not end in `_=`.
+
+A value declaration `val $x_1 , \ldots , x_n$: $T$` is a shorthand for the
+sequence of value declarations `val $x_1$: $T$; ...; val $x_n$: $T$`.
+A value definition `val $p_1 , \ldots , p_n$ = $e$` is a shorthand for the
+sequence of value definitions `val $p_1$ = $e$; ...; val $p_n$ = $e$`.
+A value definition `val $p_1 , \ldots , p_n: T$ = $e$` is a shorthand for the
+sequence of value definitions `val $p_1: T$ = $e$; ...; val $p_n: T$ = $e$`.
+
+
+Variable Declarations and Definitions
+-------------------------------------
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+Dcl ::= ‘var’ VarDcl
+PatVarDef ::= ‘var’ VarDef
+VarDcl ::= ids ‘:’ Type
+VarDef ::= PatDef
+ | ids ‘:’ Type ‘=’ ‘_’
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A variable declaration `var $x$: $T$` is equivalent to declarations
+of a _getter function_ $x$ and a _setter function_
+`$x$_=`, defined as follows:
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+def $x$: $T$
+def $x$_= ($y$: $T$): Unit
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
An implementation of a class containing variable declarations
may define these variables using variable definitions, or it may
define setter and getter functions directly.
-A variable definition ~\lstinline@var $x$: $T$ = $e$@~ introduces a
+A variable definition `var $x$: $T$ = $e$` introduces a
mutable variable with type $T$ and initial value as given by the
expression $e$. The type $T$ can be omitted, in which case the type of
-$e$ is assumed. If $T$ is given, then $e$ is expected to conform to it
-(\sref{sec:expr-typing}).
+$e$ is assumed. If $T$ is given, then $e$ is expected to
+[conform to it](#expression-typing).
-Variable definitions can alternatively have a pattern
-(\sref{sec:patterns}) as left-hand side. A variable definition
- ~\lstinline@var $p$ = $e$@~ where $p$ is a pattern other
+Variable definitions can alternatively have a [pattern](#patterns)
+as left-hand side. A variable definition
+ `var $p$ = $e$` where $p$ is a pattern other
than a simple name or a name followed by a colon and a type is expanded in the same way
-(\sref{sec:valdef})
-as a value definition ~\lstinline@val $p$ = $e$@, except that
+as a [value definition](#value-declarations-and-definitions)
+`val $p$ = $e$`, except that
the free names in $p$ are introduced as mutable variables, not values.
-The name of any declared or defined variable may not end in \lstinline@_=@.
+The name of any declared or defined variable may not end in `_=`.
-A variable definition ~\lstinline@var $x$: $T$ = _@~ can appear only
+A variable definition `var $x$: $T$ = _` can appear only
as a member of a template. It introduces a mutable field with type
\ $T$ and a default initial value. The default value depends on the
type $T$ as follows:
-\begin{quote}\begin{tabular}{ll}
-\code{0} & if $T$ is \code{Int} or one of its subrange types, \\
-\code{0L} & if $T$ is \code{Long},\\
-\lstinline@0.0f@ & if $T$ is \code{Float},\\
-\lstinline@0.0d@ & if $T$ is \code{Double},\\
-\code{false} & if $T$ is \code{Boolean},\\
-\lstinline@{}@ & if $T$ is \code{Unit}, \\
-\code{null} & for all other types $T$.
-\end{tabular}\end{quote}
+
+---------- --------------------------------------------------
+`0` if $T$ is `Int` or one of its subrange types
+`0L` if $T$ is `Long`
+`0.0f` if $T$ is `Float`
+`0.0d` if $T$ is `Double`
+`false` if $T$ is `Boolean`
+`{}` if $T$ is `Unit`
+`null` for all other types $T$
+---------- --------------------------------------------------
+
When they occur as members of a template, both forms of variable
definition also introduce a getter function $x$ which returns the
value currently assigned to the variable, as well as a setter function
-\lstinline@$x$_=@ which changes the value currently assigned to the variable.
+`$x$_=` which changes the value currently assigned to the variable.
The functions have the same signatures as for a variable declaration.
The template then has these getter and setter functions as
members, whereas the original variable cannot be accessed directly as
a template member.
-\example The following example shows how {\em properties} can be
-simulated in Scala. It defines a class \code{TimeOfDayVar} of time
-values with updatable integer fields representing hours, minutes, and
-seconds. Its implementation contains tests that allow only legal
-values to be assigned to these fields. The user code, on the other
-hand, accesses these fields just like normal variables.
-
-\begin{lstlisting}
-class TimeOfDayVar {
- private var h: Int = 0
- private var m: Int = 0
- private var s: Int = 0
-
- def hours = h
- def hours_= (h: Int) = if (0 <= h && h < 24) this.h = h
- else throw new DateError()
-
- def minutes = m
- def minutes_= (m: Int) = if (0 <= m && m < 60) this.m = m
- else throw new DateError()
-
- def seconds = s
- def seconds_= (s: Int) = if (0 <= s && s < 60) this.s = s
- else throw new DateError()
-}
-val d = new TimeOfDayVar
-d.hours = 8; d.minutes = 30; d.seconds = 0
-d.hours = 25 // throws a DateError exception
-\end{lstlisting}
-
-A variable declaration ~\lstinline@var $x_1 \commadots x_n$: $T$@~
-is a
-shorthand for the sequence of variable declarations
-~\lstinline@var $x_1$: $T$; ...; var $x_n$: $T$@.
-A variable definition ~\lstinline@var $x_1 \commadots x_n$ = $e$@~
-is a
-shorthand for the sequence of variable definitions
-~\lstinline@var $x_1$ = $e$; ...; var $x_n$ = $e$@.
-A variable definition ~\lstinline@var $x_1 \commadots x_n: T$ = $e$@~
-is a
-shorthand for the sequence of variable definitions
-~\lstinline@var $x_1: T$ = $e$; ...; var $x_n: T$ = $e$@.
+(@) The following example shows how _properties_ can be
+ simulated in Scala. It defines a class `TimeOfDayVar` of time
+ values with updatable integer fields representing hours, minutes, and
+ seconds. Its implementation contains tests that allow only legal
+ values to be assigned to these fields. The user code, on the other
+ hand, accesses these fields just like normal variables.
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ class TimeOfDayVar {
+ private var h: Int = 0
+ private var m: Int = 0
+ private var s: Int = 0
+
+ def hours = h
+ def hours_= (h: Int) = if (0 <= h && h < 24) this.h = h
+ else throw new DateError()
+
+ def minutes = m
+ def minutes_= (m: Int) = if (0 <= m && m < 60) this.m = m
+ else throw new DateError()
+
+ def seconds = s
+ def seconds_= (s: Int) = if (0 <= s && s < 60) this.s = s
+ else throw new DateError()
+ }
+ val d = new TimeOfDayVar
+ d.hours = 8; d.minutes = 30; d.seconds = 0
+ d.hours = 25 // throws a DateError exception
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+A variable declaration `var $x_1 , \ldots , x_n$: $T$` is a shorthand for the
+sequence of variable declarations `var $x_1$: $T$; ...; var $x_n$: $T$`.
+A variable definition `var $x_1 , \ldots , x_n$ = $e$` is a shorthand for the
+sequence of variable definitions `var $x_1$ = $e$; ...; var $x_n$ = $e$`.
+A variable definition `var $x_1 , \ldots , x_n: T$ = $e$` is a shorthand for
+the sequence of variable definitions
+`var $x_1: T$ = $e$; ...; var $x_n: T$ = $e$`.
Type Declarations and Type Aliases
----------------------------------
-\label{sec:typedcl}
-\label{sec:typealias}
+<!-- TODO: Higher-kinded tdecls should have a separate section -->
-\todo{Higher-kinded tdecls should have a separate section}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.grammar}
+Dcl ::= ‘type’ {nl} TypeDcl
+TypeDcl ::= id [TypeParamClause] [‘>:’ Type] [‘<:’ Type]
+Def ::= type {nl} TypeDef
+TypeDef ::= id [TypeParamClause] ‘=’ Type
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\syntax\begin{lstlisting}
- Dcl ::= `type' {nl} TypeDcl
- TypeDcl ::= id [TypeParamClause] [`>:' Type] [`<:' Type]
- Def ::= type {nl} TypeDef
- TypeDef ::= id [TypeParamClause] `=' Type
-\end{lstlisting}
-
-%@M
-A {\em type declaration} ~\lstinline@type $t$[$\tps\,$] >: $L$ <: $U$@~ declares
+A _type declaration_ `type $t$[$\mathit{tps}\,$] >: $L$ <: $U$` declares
$t$ to be an abstract type with lower bound type $L$ and upper bound
-type $U$. If the type parameter clause \lstinline@[$\tps\,$]@ is omitted, $t$ abstracts over a first-order type, otherwise $t$ stands for a type constructor that accepts type arguments as described by the type parameter clause.
+type $U$. If the type parameter clause `[$\mathit{tps}\,$]` is omitted, $t$ abstracts over a first-order type, otherwise $t$ stands for a type constructor that accepts type arguments as described by the type parameter clause.
-%@M
If a type declaration appears as a member declaration of a
type, implementations of the type may implement $t$ with any type $T$
for which $L \conforms T \conforms U$. It is a compile-time error if
$L$ does not conform to $U$. Either or both bounds may be omitted.
If the lower bound $L$ is absent, the bottom type
-\lstinline@scala.Nothing@ is assumed. If the upper bound $U$ is absent,
-the top type \lstinline@scala.Any@ is assumed.
+`scala.Nothing` is assumed. If the upper bound $U$ is absent,
+the top type `scala.Any` is assumed.
-%@M
A type constructor declaration imposes additional restrictions on the
concrete types for which $t$ may stand. Besides the bounds $L$ and
$U$, the type parameter clause may impose higher-order bounds and
-variances, as governed by the conformance of type constructors
-(\sref{sec:conformance}).
+variances, as governed by the [conformance of type constructors](#conformance).
-%@M
-The scope of a type parameter extends over the bounds ~\lstinline@>: $L$ <: $U$@ and the type parameter clause $\tps$ itself. A
+The scope of a type parameter extends over the bounds `>: $L$ <: $U$` and the type parameter clause $\mathit{tps}$ itself. A
higher-order type parameter clause (of an abstract type constructor
$tc$) has the same kind of scope, restricted to the declaration of the
type parameter $tc$.
-To illustrate nested scoping, these declarations are all equivalent: ~\lstinline@type t[m[x] <: Bound[x], Bound[x]]@, ~\lstinline@type t[m[x] <: Bound[x], Bound[y]]@ and ~\lstinline@type t[m[x] <: Bound[x], Bound[_]]@, as the scope of, e.g., the type parameter of $m$ is limited to the declaration of $m$. In all of them, $t$ is an abstract type member that abstracts over two type constructors: $m$ stands for a type constructor that takes one type parameter and that must be a subtype of $Bound$, $t$'s second type constructor parameter. ~\lstinline@t[MutableList, Iterable]@ is a valid use of $t$.
+To illustrate nested scoping, these declarations are all equivalent: `type t[m[x] <: Bound[x], Bound[x]]`, `type t[m[x] <: Bound[x], Bound[y]]` and `type t[m[x] <: Bound[x], Bound[_]]`, as the scope of, e.g., the type parameter of $m$ is limited to the declaration of $m$. In all of them, $t$ is an abstract type member that abstracts over two type constructors: $m$ stands for a type constructor that takes one type parameter and that must be a subtype of $Bound$, $t$'s second type constructor parameter. `t[MutableList, Iterable]` is a valid use of $t$.
-A {\em type alias} ~\lstinline@type $t$ = $T$@~ defines $t$ to be an alias
+A _type alias_ `type $t$ = $T$` defines $t$ to be an alias
name for the type $T$. The left hand side of a type alias may
-have a type parameter clause, e.g. ~\lstinline@type $t$[$\tps\,$] = $T$@. The scope
+have a type parameter clause, e.g. `type $t$[$\mathit{tps}\,$] = $T$`. The scope
of a type parameter extends over the right hand side $T$ and the
-type parameter clause $\tps$ itself.
+type parameter clause $\mathit{tps}$ itself.
-The scope rules for definitions (\sref{sec:defs}) and type parameters
-(\sref{sec:funsigs}) make it possible that a type name appears in its
+The scope rules for [definitions](#basic-declarations-and-definitions)
+and [type parameters](#function-declarations-and-definitions)
+make it possible that a type name appears in its
own bound or in its right-hand side. However, it is a static error if
a type alias refers recursively to the defined type constructor itself.
-That is, the type $T$ in a type alias ~\lstinline@type $t$[$\tps\,$] = $T$@~ may not
+That is, the type $T$ in a type alias `type $t$[$\mathit{tps}\,$] = $T$` may not
refer directly or indirectly to the name $t$. It is also an error if
an abstract type is directly or indirectly its own upper or lower bound.
-\example The following are legal type declarations and definitions:
-\begin{lstlisting}
-type IntList = List[Integer]
-type T <: Comparable[T]
-type Two[A] = Tuple2[A, A]
-type MyCollection[+X] <: Iterable[X]
-\end{lstlisting}
+(@) The following are legal type declarations and definitions:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ type IntList = List[Integer]
+ type T <: Comparable[T]
+ type Two[A] = Tuple2[A, A]
+ type MyCollection[+X] <: Iterable[X]
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ The following are illegal:
-The following are illegal:
-\begin{lstlisting}
-type Abs = Comparable[Abs] // recursive type alias
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.scala}
+ type Abs = Comparable[Abs] // recursive type alias
-type S <: T // S, T are bounded by themselves.
-type T <: S
+ type S <: T // S, T are bounded by themselves.
+ type T <: S
-type T >: Comparable[T.That] // Cannot select from T.
- // T is a type, not a value
-type MyCollection <: Iterable // Type constructor members must explicitly state their type parameters.
-\end{lstlisting}
+ type T >: Comparable[T.That] // Cannot select from T.
+ // T is a type, not a value
+ type MyCollection <: Iterable // Type constructor members must explicitly
+ // state their type parameters.
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-If a type alias ~\lstinline@type $t$[$\tps\,$] = $S$@~ refers to a class type
+If a type alias `type $t$[$\mathit{tps}\,$] = $S$` refers to a class type
$S$, the name $t$ can also be used as a constructor for
objects of type $S$.
-\example The \code{Predef} object contains a definition which establishes \code{Pair}
-as an alias of the parameterized class \code{Tuple2}:
-\begin{lstlisting}
-type Pair[+A, +B] = Tuple2[A, B]
-object Pair {
- def apply[A, B](x: A, y: B) = Tuple2(x, y)
- def unapply[A, B](x: Tuple2[A, B]): Option[Tuple2[A, B]] = Some(x)
-}
-\end{lstlisting}
-As a consequence, for any two types $S$ and $T$, the type
-~\lstinline@Pair[$S$, $T\,$]@~ is equivalent to the type ~\lstinline@Tuple2[$S$, $T\,$]@.
-\code{Pair} can also be used as a constructor instead of \code{Tuple2}, as in:
-\begin{lstlisting}
-val x: Pair[Int, String] = new Pair(1, "abc")
-\end{lstlisting}
-
-\section{Type Parameters}\label{sec:type-params}
-
-\syntax\begin{lstlisting}
- TypeParamClause ::= `[' VariantTypeParam {`,' VariantTypeParam} `]'
- VariantTypeParam ::= {Annotation} [`+' | `-'] TypeParam
- TypeParam ::= (id | `_') [TypeParamClause] [`>:' Type] [`<:' Type] [`:' Type]
-\end{lstlisting}
+(@) The `Predef` object contains a definition which establishes `Pair`
+ as an alias of the parameterized class `Tuple2`:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ type Pair[+A, +B] = Tuple2[A, B]
+ object Pair {
+ def apply[A, B](x: A, y: B) = Tuple2(x, y)
+ def unapply[A, B](x: Tuple2[A, B]): Option[Tuple2[A, B]] = Some(x)
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ As a consequence, for any two types $S$ and $T$, the type
+ `Pair[$S$, $T\,$]` is equivalent to the type `Tuple2[$S$, $T\,$]`.
+ `Pair` can also be used as a constructor instead of `Tuple2`, as in:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ val x: Pair[Int, String] = new Pair(1, "abc")
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+Type Parameters
+---------------
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+TypeParamClause ::= ‘[’ VariantTypeParam {‘,’ VariantTypeParam} ‘]’
+VariantTypeParam ::= {Annotation} [‘+’ | ‘-’] TypeParam
+TypeParam ::= (id | ‘_’) [TypeParamClause] [‘>:’ Type] [‘<:’ Type] [‘:’ Type]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Type parameters appear in type definitions, class definitions, and
function definitions. In this section we consider only type parameter
-definitions with lower bounds ~\lstinline@>: $L$@~ and upper bounds
-~\lstinline@<: $U$@~ whereas a discussion of context bounds
-~\lstinline@: $U$@~ and view bounds ~\lstinline@<% $U$@~
-is deferred to Section~\ref{sec:context-bounds}.
+definitions with lower bounds `>: $L$` and upper bounds
+`<: $U$` whereas a discussion of context bounds
+`: $U$` and view bounds `<% $U$`
+is deferred to [here](#context-bounds-and-view-bounds).
The most general form of a first-order type parameter is
-~\lstinline!$@a_1\ldots@a_n$ $\pm$ $t$ >: $L$ <: $U$!.
+`$@a_1 \ldots @a_n$ $\pm$ $t$ >: $L$ <: $U$`.
Here, $L$, and $U$ are lower and upper bounds that
constrain possible type arguments for the parameter. It is a
-compile-time error if $L$ does not conform to $U$. $\pm$ is a {\em
-variance}, i.e.\ an optional prefix of either \lstinline@+@, or
-\lstinline@-@. One or more annotations may precede the type parameter.
+compile-time error if $L$ does not conform to $U$. $\pm$ is a _variance_, i.e.\ an optional prefix of either `+`, or
+`-`. One or more annotations may precede the type parameter.
\comment{
The upper bound $U$ in a type parameter clauses may not be a final
@@ -422,51 +365,55 @@ class. The lower bound may not denote a value type.\todo{Why}
\comment{@M TODO this is a pretty awkward description of scoping and distinctness of binders}
The names of all type parameters must be pairwise different in their enclosing type parameter clause. The scope of a type parameter includes in each case the whole type parameter clause. Therefore it is possible that a type parameter appears as part of its own bounds or the bounds of other type parameters in the same clause. However, a type parameter may not be bounded directly or indirectly by itself.\
-A type constructor parameter adds a nested type parameter clause to the type parameter. The most general form of a type constructor parameter is ~\lstinline!$@a_1\ldots@a_n$ $\pm$ $t[\tps\,]$ >: $L$ <: $U$!.
-
-The above scoping restrictions are generalized to the case of nested type parameter clauses, which declare higher-order type parameters. Higher-order type parameters (the type parameters of a type parameter $t$) are only visible in their immediately surrounding parameter clause (possibly including clauses at a deeper nesting level) and in the bounds of $t$. Therefore, their names must only be pairwise different from the names of other visible parameters. Since the names of higher-order type parameters are thus often irrelevant, they may be denoted with a `\lstinline@_@', which is nowhere visible.
-
-\example Here are some well-formed type parameter clauses:
-\begin{lstlisting}
-[S, T]
-[@specialized T, U]
-[Ex <: Throwable]
-[A <: Comparable[B], B <: A]
-[A, B >: A, C >: A <: B]
-[M[X], N[X]]
-[M[_], N[_]] // equivalent to previous clause
-[M[X <: Bound[X]], Bound[_]]
-[M[+X] <: Iterable[X]]
-\end{lstlisting}
-The following type parameter clauses are illegal:
-\begin{lstlisting}
-[A >: A] // illegal, `A' has itself as bound
-[A <: B, B <: C, C <: A] // illegal, `A' has itself as bound
-[A, B, C >: A <: B] // illegal lower bound `A' of `C' does
- // not conform to upper bound `B'.
-\end{lstlisting}
-
-\section{Variance Annotations}\label{sec:variances}
+A type constructor parameter adds a nested type parameter clause to the type parameter. The most general form of a type constructor parameter is `$@a_1\ldots@a_n$ $\pm$ $t[\mathit{tps}\,]$ >: $L$ <: $U$`.
+
+The above scoping restrictions are generalized to the case of nested type parameter clauses, which declare higher-order type parameters. Higher-order type parameters (the type parameters of a type parameter $t$) are only visible in their immediately surrounding parameter clause (possibly including clauses at a deeper nesting level) and in the bounds of $t$. Therefore, their names must only be pairwise different from the names of other visible parameters. Since the names of higher-order type parameters are thus often irrelevant, they may be denoted with a ‘_’, which is nowhere visible.
+
+(@) Here are some well-formed type parameter clauses:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ [S, T]
+ [@specialized T, U]
+ [Ex <: Throwable]
+ [A <: Comparable[B], B <: A]
+ [A, B >: A, C >: A <: B]
+ [M[X], N[X]]
+ [M[_], N[_]] // equivalent to previous clause
+ [M[X <: Bound[X]], Bound[_]]
+ [M[+X] <: Iterable[X]]
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ The following type parameter clauses are illegal:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ [A >: A] // illegal, `A' has itself as bound
+ [A <: B, B <: C, C <: A] // illegal, `A' has itself as bound
+ [A, B, C >: A <: B] // illegal lower bound `A' of `C' does
+ // not conform to upper bound `B'.
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+Variance Annotations
+--------------------
Variance annotations indicate how instances of parameterized types
-vary with respect to subtyping (\sref{sec:conformance}). A
-`\lstinline@+@' variance indicates a covariant dependency, a
-`\lstinline@-@' variance indicates a contravariant dependency, and a
+vary with respect to [subtyping](#conformance). A
+‘+’ variance indicates a covariant dependency, a
+‘-’ variance indicates a contravariant dependency, and a
missing variance indication indicates an invariant dependency.
-%@M
A variance annotation constrains the way the annotated type variable
may appear in the type or class which binds the type parameter. In a
-type definition ~\lstinline@type $T$[$\tps\,$] = $S$@, or a type
-declaration ~\lstinline@type $T$[$\tps\,$] >: $L$ <: $U$@~ type parameters labeled
-`\lstinline@+@' must only appear in covariant position whereas
-type parameters labeled `\lstinline@-@' must only appear in contravariant
+type definition `type $T$[$\mathit{tps}\,$] = $S$`, or a type
+declaration `type $T$[$\mathit{tps}\,$] >: $L$ <: $U$` type parameters labeled
+‘+’ must only appear in covariant position whereas
+type parameters labeled ‘-’ must only appear in contravariant
position. Analogously, for a class definition
-~\lstinline@class $C$[$\tps\,$]($\ps\,$) extends $T$ { $x$: $S$ => ...}@,
+`class $C$[$\mathit{tps}\,$]($\mathit{ps}\,$) extends $T$ { $x$: $S$ => ...}`,
type parameters labeled
-`\lstinline@+@' must only appear in covariant position in the
+‘+’ must only appear in covariant position in the
self type $S$ and the template $T$, whereas type
-parameters labeled `\lstinline@-@' must only appear in contravariant
+parameters labeled ‘-’ must only appear in contravariant
position.
The variance position of a type parameter in a type or template is
@@ -474,141 +421,143 @@ defined as follows. Let the opposite of covariance be contravariance,
and the opposite of invariance be itself. The top-level of the type
or template is always in covariant position. The variance position
changes at the following constructs.
-\begin{itemize}
-\item
-The variance position of a method parameter is the opposite of the
-variance position of the enclosing parameter clause.
-\item
-The variance position of a type parameter is the opposite of the
-variance position of the enclosing type parameter clause.
-\item
-The variance position of the lower bound of a type declaration or type parameter
-is the opposite of the variance position of the type declaration or parameter.
-\item
-The type of a mutable variable is always in invariant position.
-\item
-The prefix $S$ of a type selection \lstinline@$S$#$T$@ is always in invariant position.
-\item
-For a type argument $T$ of a type ~\lstinline@$S$[$\ldots T \ldots$ ]@: If the
-corresponding type parameter is invariant, then $T$ is in
-invariant position. If the corresponding type parameter is
-contravariant, the variance position of $T$ is the opposite of
-the variance position of the enclosing type ~\lstinline@$S$[$\ldots T \ldots$ ]@.
-\end{itemize}
-\todo{handle type aliases}
-References to the type parameters in object-private values, variables,
-or methods (\sref{sec:modifiers}) of the class are not checked for their variance
-position. In these members the type parameter may appear anywhere
-without restricting its legal variance annotations.
-
-\example The following variance annotation is legal.
-\begin{lstlisting}
-abstract class P[+A, +B] {
- def fst: A; def snd: B
-}
-\end{lstlisting}
-With this variance annotation, type instances
-of $P$ subtype covariantly with respect to their arguments.
-For instance,
-\begin{lstlisting}
-P[IOException, String] <: P[Throwable, AnyRef] .
-\end{lstlisting}
-
-If the members of $P$ are mutable variables,
-the same variance annotation becomes illegal.
-\begin{lstlisting}
-abstract class Q[+A, +B](x: A, y: B) {
- var fst: A = x // **** error: illegal variance:
- var snd: B = y // `A', `B' occur in invariant position.
-}
-\end{lstlisting}
-If the mutable variables are object-private, the class definition
-becomes legal again:
-\begin{lstlisting}
-abstract class R[+A, +B](x: A, y: B) {
- private[this] var fst: A = x // OK
- private[this] var snd: B = y // OK
-}
-\end{lstlisting}
-
-\example The following variance annotation is illegal, since $a$ appears
-in contravariant position in the parameter of \code{append}:
-
-\begin{lstlisting}
-abstract class Sequence[+A] {
- def append(x: Sequence[A]): Sequence[A]
- // **** error: illegal variance:
- // `A' occurs in contravariant position.
-}
-\end{lstlisting}
-The problem can be avoided by generalizing the type of \code{append}
-by means of a lower bound:
-
-\begin{lstlisting}
-abstract class Sequence[+A] {
- def append[B >: A](x: Sequence[B]): Sequence[B]
-}
-\end{lstlisting}
-\example Here is a case where a contravariant type parameter is useful.
+- The variance position of a method parameter is the opposite of the
+ variance position of the enclosing parameter clause.
+- The variance position of a type parameter is the opposite of the
+ variance position of the enclosing type parameter clause.
+- The variance position of the lower bound of a type declaration or type parameter
+ is the opposite of the variance position of the type declaration or parameter.
+- The type of a mutable variable is always in invariant position.
+- The prefix $S$ of a type selection `$S$#$T$` is always in invariant position.
+- For a type argument $T$ of a type `$S$[$\ldots T \ldots$ ]`: If the
+ corresponding type parameter is invariant, then $T$ is in
+ invariant position. If the corresponding type parameter is
+ contravariant, the variance position of $T$ is the opposite of
+ the variance position of the enclosing type `$S$[$\ldots T \ldots$ ]`.
+
+<!-- TODO: handle type aliases -->
+
+References to the type parameters in
+[object-private values, variables, or methods](#modifiers) of the class are not
+checked for their variance position. In these members the type parameter may
+appear anywhere without restricting its legal variance annotations.
+
+(@) The following variance annotation is legal.
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ abstract class P[+A, +B] {
+ def fst: A; def snd: B
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ With this variance annotation, type instances
+ of $P$ subtype covariantly with respect to their arguments.
+ For instance,
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ P[IOException, String] <: P[Throwable, AnyRef]
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ If the members of $P$ are mutable variables,
+ the same variance annotation becomes illegal.
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ abstract class Q[+A, +B](x: A, y: B) {
+ var fst: A = x // **** error: illegal variance:
+ var snd: B = y // `A', `B' occur in invariant position.
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ If the mutable variables are object-private, the class definition
+ becomes legal again:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ abstract class R[+A, +B](x: A, y: B) {
+ private[this] var fst: A = x // OK
+ private[this] var snd: B = y // OK
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+(@) The following variance annotation is illegal, since $a$ appears
+ in contravariant position in the parameter of `append`:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ abstract class Sequence[+A] {
+ def append(x: Sequence[A]): Sequence[A]
+ // **** error: illegal variance:
+ // `A' occurs in contravariant position.
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ The problem can be avoided by generalizing the type of `append`
+ by means of a lower bound:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ abstract class Sequence[+A] {
+ def append[B >: A](x: Sequence[B]): Sequence[B]
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+(@) Here is a case where a contravariant type parameter is useful.
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ abstract class OutputChannel[-A] {
+ def write(x: A): Unit
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ With that annotation, we have that
+ `OutputChannel[AnyRef]` conforms to `OutputChannel[String]`.
+ That is, a
+ channel on which one can write any object can substitute for a channel
+ on which one can write only strings.
-\begin{lstlisting}
-abstract class OutputChannel[-A] {
- def write(x: A): Unit
-}
-\end{lstlisting}
-With that annotation, we have that
-\lstinline@OutputChannel[AnyRef]@ conforms to \lstinline@OutputChannel[String]@.
-That is, a
-channel on which one can write any object can substitute for a channel
-on which one can write only strings.
Function Declarations and Definitions
-------------------------------------
-\label{sec:funsigs}
-
-\syntax\begin{lstlisting}
-Dcl ::= `def' FunDcl
-FunDcl ::= FunSig `:' Type
-Def ::= `def' FunDef
-FunDef ::= FunSig [`:' Type] `=' Expr
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.grammar}
+Dcl ::= ‘def’ FunDcl
+FunDcl ::= FunSig ‘:’ Type
+Def ::= ‘def’ FunDef
+FunDef ::= FunSig [‘:’ Type] ‘=’ Expr
FunSig ::= id [FunTypeParamClause] ParamClauses
-FunTypeParamClause ::= `[' TypeParam {`,' TypeParam} `]'
-ParamClauses ::= {ParamClause} [[nl] `(' `implicit' Params `)']
-ParamClause ::= [nl] `(' [Params] `)'}
-Params ::= Param {`,' Param}
-Param ::= {Annotation} id [`:' ParamType] [`=' Expr]
+FunTypeParamClause ::= ‘[’ TypeParam {‘,’ TypeParam} ‘]’
+ParamClauses ::= {ParamClause} [[nl] ‘(’ ‘implicit Params ‘)’]
+ParamClause ::= [nl] ‘(’ [Params] ‘)’}
+Params ::= Param {‘,’ Param}
+Param ::= {Annotation} id [‘:’ ParamType] [‘=’ Expr]
ParamType ::= Type
- | `=>' Type
- | Type `*'
-\end{lstlisting}
+ | ‘=>’ Type
+ | Type ‘*’
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-A function declaration has the form ~\lstinline@def $f\,\psig$: $T$@, where
-$f$ is the function's name, $\psig$ is its parameter
+A function declaration has the form `def $f\,\mathit{psig}$: $T$`, where
+$f$ is the function's name, $\mathit{psig}$ is its parameter
signature and $T$ is its result type. A function definition
-~\lstinline@def $f\,\psig$: $T$ = $e$@~ also includes a {\em function body} $e$,
+`def $f\,\mathit{psig}$: $T$ = $e$` also includes a _function body_ $e$,
i.e.\ an expression which defines the function's result. A parameter
-signature consists of an optional type parameter clause \lstinline@[$\tps\,$]@,
+signature consists of an optional type parameter clause `[$\mathit{tps}\,$]`,
followed by zero or more value parameter clauses
-~\lstinline@($\ps_1$)$\ldots$($\ps_n$)@. Such a declaration or definition
+`($\mathit{ps}_1$)$\ldots$($\mathit{ps}_n$)`. Such a declaration or definition
introduces a value with a (possibly polymorphic) method type whose
parameter types and result type are as given.
-The type of the function body is expected to conform (\sref{sec:expr-typing})
+The type of the function body is expected to [conform](#expr-typing)
to the function's declared
result type, if one is given. If the function definition is not
recursive, the result type may be omitted, in which case it is
determined from the packed type of the function body.
-A type parameter clause $\tps$ consists of one or more type
-declarations (\sref{sec:typedcl}), which introduce type parameters,
-possibly with bounds. The scope of a type parameter includes
+A type parameter clause $\mathit{tps}$ consists of one or more
+[type declarations](#type-declarations-and-type-aliases), which introduce type
+parameters, possibly with bounds. The scope of a type parameter includes
the whole signature, including any of the type parameter bounds as
well as the function body, if it is present.
-A value parameter clause $\ps$ consists of zero or more formal
-parameter bindings such as \lstinline@$x$: $T$@ or \lstinline@$x: T = e$@, which bind value
+A value parameter clause $\mathit{ps}$ consists of zero or more formal
+parameter bindings such as `$x$: $T$` or `$x: T = e$`, which bind value
parameters and associate them with their types. Each value parameter
declaration may optionally define a default argument. The default argument
expression $e$ is type-checked with an expected type $T'$ obtained
@@ -616,166 +565,179 @@ by replacing all occurences of the function's type parameters in $T$ by
the undefined type.
For every parameter $p_{i,j}$ with a default argument a method named
-\lstinline@$f\Dollar$default$\Dollar$n@ is generated which computes the default argument
+`$f\$$default$\$$n` is generated which computes the default argument
expression. Here, $n$ denotes the parameter's position in the method
declaration. These methods are parametrized by the type parameter clause
-\lstinline@[$\tps\,$]@ and all value parameter clauses
-~\lstinline@($\ps_1$)$\ldots$($\ps_{i-1}$)@ preceeding $p_{i,j}$.
-The \lstinline@$f\Dollar$default$\Dollar$n@ methods are inaccessible for
+`[$\mathit{tps}\,$]` and all value parameter clauses
+`($\mathit{ps}_1$)$\ldots$($\mathit{ps}_{i-1}$)` preceeding $p_{i,j}$.
+The `$f\$$default$\$$n` methods are inaccessible for
user programs.
-The scope of a formal value parameter name $x$ comprises all subsequent parameter
-clauses, as well as the method return type and the function body, if
-they are given.\footnote{However, at present singleton types of method
-parameters may only appear in the method body; so {\em dependent method
-types} are not supported.} Both type parameter names
-and value parameter names must be pairwise distinct.
-
-\example In the method
-\begin{lstlisting}
-def compare[T](a: T = 0)(b: T = a) = (a == b)
-\end{lstlisting}
-the default expression \code{0} is type-checked with an undefined expected
-type. When applying \code{compare()}, the default value \code{0} is inserted
-and \code{T} is instantiated to \code{Int}. The methods computing the default
-arguments have the form:
-\begin{lstlisting}
-def compare$\Dollar$default$\Dollar$1[T]: Int = 0
-def compare$\Dollar$default$\Dollar$2[T](a: T): T = a
-\end{lstlisting}
-
-\subsection{By-Name Parameters}\label{sec:by-name-params}
-
-\syntax\begin{lstlisting}
-ParamType ::= `=>' Type
-\end{lstlisting}
-
-The type of a value parameter may be prefixed by \code{=>}, e.g.\
-~\lstinline@$x$: => $T$@. The type of such a parameter is then the
-parameterless method type ~\lstinline@=> $T$@. This indicates that the
+The scope of a formal value parameter name $x$ comprises all subsequent
+parameter clauses, as well as the method return type and the function body, if
+they are given [^5]. Both type parameter names and value parameter names must
+be pairwise distinct.
+
+[^5]: However, at present singleton types of method parameters may only appear
+ in the method body; so _dependent method types_ are not supported.
+
+(@) In the method
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ def compare[T](a: T = 0)(b: T = a) = (a == b)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ the default expression `0` is type-checked with an undefined expected
+ type. When applying `compare()`, the default value `0` is inserted
+ and `T` is instantiated to `Int`. The methods computing the default
+ arguments have the form:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ def compare$\$$default$\$$1[T]: Int = 0
+ def compare$\$$default$\$$2[T](a: T): T = a
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+### By-Name Parameters
+
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.grammar}
+ParamType ::= ‘=>’ Type
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The type of a value parameter may be prefixed by `=>`, e.g.\
+`$x$: => $T$`. The type of such a parameter is then the
+parameterless method type `=> $T$`. This indicates that the
corresponding argument is not evaluated at the point of function
application, but instead is evaluated at each use within the
-function. That is, the argument is evaluated using {\em call-by-name}.
+function. That is, the argument is evaluated using _call-by-name_.
The by-name modifier is disallowed for parameters of classes that
-carry a \code{val} or \code{var} prefix, including parameters of case
-classes for which a \code{val} prefix is implicitly generated. The
-by-name modifier is also disallowed for implicit parameters (\sref{sec:impl-params}).
+carry a `val` or `var` prefix, including parameters of case
+classes for which a `val` prefix is implicitly generated. The
+by-name modifier is also disallowed for
+[implicit parameters](#implicit-parameters).
+
+(@) The declaration
-\example The declaration
-\begin{lstlisting}
-def whileLoop (cond: => Boolean) (stat: => Unit): Unit
-\end{lstlisting}
-indicates that both parameters of \code{whileLoop} are evaluated using
-call-by-name.
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ def whileLoop (cond: => Boolean) (stat: => Unit): Unit
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\subsection{Repeated Parameters}\label{sec:repeated-params}
+ indicates that both parameters of `whileLoop` are evaluated using
+ call-by-name.
-\syntax\begin{lstlisting}
-ParamType ::= Type `*'
-\end{lstlisting}
+
+### Repeated Parameters
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.grammar}
+ParamType ::= Type ‘*’
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The last value parameter of a parameter section may be suffixed by
-``\code{*}'', e.g.\ ~\lstinline@(..., $x$:$T$*)@. The type of such a
-{\em repeated} parameter inside the method is then the sequence type
-\lstinline@scala.Seq[$T$]@. Methods with repeated parameters
-\lstinline@$T$*@ take a variable number of arguments of type $T$.
-That is, if a method $m$ with type ~\lstinline@($p_1:T_1 \commadots p_n:T_n,
-p_s:S$*)$U$@~ is applied to arguments $(e_1 \commadots e_k)$ where $k \geq
-n$, then $m$ is taken in that application to have type $(p_1:T_1
-\commadots p_n:T_n, p_s:S \commadots p_{s'}S)U$, with $k - n$ occurrences of type
-$S$ where any parameter names beyond $p_s$ are fresh. The only exception to this rule is if the last argument is
-marked to be a {\em sequence argument} via a \lstinline@_*@ type
+“*”, e.g. `(..., $x$:$T$*)`. The type of such a
+_repeated_ parameter inside the method is then the sequence type
+`scala.Seq[$T$]`. Methods with repeated parameters
+`$T$*` take a variable number of arguments of type $T$.
+That is, if a method $m$ with type
+`($p_1:T_1 , \ldots , p_n:T_n, p_s:S$*)$U$` is applied to arguments
+$(e_1 , \ldots , e_k)$ where $k \geq n$, then $m$ is taken in that application
+to have type $(p_1:T_1 , \ldots , p_n:T_n, p_s:S , \ldots , p_{s'}S)U$, with
+$k - n$ occurrences of type
+$S$ where any parameter names beyond $p_s$ are fresh. The only exception to
+this rule is if the last argument is
+marked to be a _sequence argument_ via a `_*` type
annotation. If $m$ above is applied to arguments
-~\lstinline@($e_1 \commadots e_n, e'$: _*)@, then the type of $m$ in
+`($e_1 , \ldots , e_n, e'$: _*)`, then the type of $m$ in
that application is taken to be
-~\lstinline@($p_1:T_1\commadots p_n:T_n,p_{s}:$scala.Seq[$S$])@.
+`($p_1:T_1, \ldots , p_n:T_n,p_{s}:$scala.Seq[$S$])`.
It is not allowed to define any default arguments in a parameter section
with a repeated parameter.
-\example The following method definition computes the sum of the squares of a variable number
-of integer arguments.
-\begin{lstlisting}
-def sum(args: Int*) = {
- var result = 0
- for (arg <- args) result += arg * arg
- result
-}
-\end{lstlisting}
-The following applications of this method yield \code{0}, \code{1},
-\code{6}, in that order.
-\begin{lstlisting}
-sum()
-sum(1)
-sum(1, 2, 3)
-\end{lstlisting}
-Furthermore, assume the definition:
-\begin{lstlisting}
-val xs = List(1, 2, 3)
-\end{lstlisting}
-The following application of method \lstinline@sum@ is ill-formed:
-\begin{lstlisting}
-sum(xs) // ***** error: expected: Int, found: List[Int]
-\end{lstlisting}
-By contrast, the following application is well formed and yields again
-the result \code{6}:
-\begin{lstlisting}
-sum(xs: _*)
-\end{lstlisting}
-
-\subsection{Procedures}\label{sec:procedures}
-
-\syntax\begin{lstlisting}
- FunDcl ::= FunSig
- FunDef ::= FunSig [nl] `{' Block `}'
-\end{lstlisting}
+(@) The following method definition computes the sum of the squares of a
+ variable number of integer arguments.
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ def sum(args: Int*) = {
+ var result = 0
+ for (arg <- args) result += arg * arg
+ result
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ The following applications of this method yield `0`, `1`,
+ `6`, in that order.
+
+ ~~~~~~~~~~~~~~~~~ {.scala}
+ sum()
+ sum(1)
+ sum(1, 2, 3)
+ ~~~~~~~~~~~~~~~~~
+
+ Furthermore, assume the definition:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ val xs = List(1, 2, 3)
+ ~~~~~~~~~~~~~~~~~~~~~~~
+
+ The following application of method `sum` is ill-formed:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ sum(xs) // ***** error: expected: Int, found: List[Int]
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ By contrast, the following application is well formed and yields again
+ the result `6`:
+
+ ~~~~~~~~~~~~ {.scala}
+ sum(xs: _*)
+ ~~~~~~~~~~~~
+
+
+### Procedures
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.grammar}
+FunDcl ::= FunSig
+FunDef ::= FunSig [nl] ‘{’ Block ‘}’
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Special syntax exists for procedures, i.e.\ functions that return the
\verb@Unit@ value \verb@{}@.
A procedure declaration is a function declaration where the result type
is omitted. The result type is then implicitly completed to the
-\verb@Unit@ type. E.g., ~\lstinline@def $f$($\ps$)@~ is equivalent to
-~\lstinline@def $f$($\ps$): Unit@.
+\verb@Unit@ type. E.g., `def $f$($\mathit{ps}$)` is equivalent to
+`def $f$($\mathit{ps}$): Unit`.
A procedure definition is a function definition where the result type
and the equals sign are omitted; its defining expression must be a block.
-E.g., ~\lstinline@def $f$($\ps$) {$\stats$}@~ is equivalent to
-~\lstinline@def $f$($\ps$): Unit = {$\stats$}@.
+E.g., `def $f$($\mathit{ps}$) {$\mathit{stats}$}` is equivalent to
+`def $f$($\mathit{ps}$): Unit = {$\mathit{stats}$}`.
-\example Here is a declaration and a definition of a procedure named \lstinline@write@:
-\begin{lstlisting}
-trait Writer {
- def write(str: String)
-}
-object Terminal extends Writer {
- def write(str: String) { System.out.println(str) }
-}
-\end{lstlisting}
-The code above is implicitly completed to the following code:
-\begin{lstlisting}
-trait Writer {
- def write(str: String): Unit
-}
-object Terminal extends Writer {
- def write(str: String): Unit = { System.out.println(str) }
-}
-\end{lstlisting}
+(@) Here is a declaration and a definition of a procedure named `write`:
-\subsection{Method Return Type Inference}\label{sec:meth-type-inf}
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ trait Writer {
+ def write(str: String)
+ }
+ object Terminal extends Writer {
+ def write(str: String) { System.out.println(str) }
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\comment{
-Functions that are members of a class $C$ may define parameters
-without type annotations. The types of such parameters are inferred as
-follows. Say, a method $m$ in a class $C$ has a parameter $p$ which
-does not have a type annotation. We first determine methods $m'$ in
-$C$ that might be overridden (\sref{sec:overriding}) by $m$, assuming
-that appropriate types are assigned to all parameters of $m$ whose
-types are missing. If there is exactly one such method, the type of
-the parameter corresponding to $p$ in that method -- seen as a member
-of $C$ -- is assigned to $p$. It is a compile-time error if there are
-several such overridden methods $m'$, or if there is none.
-}
+ The code above is implicitly completed to the following code:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ trait Writer {
+ def write(str: String): Unit
+ }
+ object Terminal extends Writer {
+ def write(str: String): Unit = { System.out.println(str) }
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+### Method Return Type Inference
A class member definition $m$ that overrides some other function $m'$
in a base class of $C$ may leave out the return type, even if it is
@@ -786,110 +748,61 @@ right-hand side of $m$ can be determined, which is then taken as the
return type of $m$. Note that $R$ may be different from $R'$, as long
as $R$ conforms to $R'$.
-\comment{
-\example Assume the following definitions:
-\begin{lstlisting}
-trait I[A] {
- def f(x: A)(y: A): A
-}
-class C extends I[Int] {
- def f(x)(y) = x + y
-}
-\end{lstlisting}
-Here, the parameter and return types of \lstinline@f@ in \lstinline@C@ are
-inferred from the corresponding types of \lstinline@f@ in \lstinline@I@. The
-signature of \lstinline@f@ in \lstinline@C@ is thus inferred to be
-\begin{lstlisting}
- def f(x: Int)(y: Int): Int
-\end{lstlisting}
-}
-
-\example Assume the following definitions:
-\begin{lstlisting}
-trait I {
- def factorial(x: Int): Int
-}
-class C extends I {
- def factorial(x: Int) = if (x == 0) 1 else x * factorial(x - 1)
-}
-\end{lstlisting}
-Here, it is OK to leave out the result type of \lstinline@factorial@
-in \lstinline@C@, even though the method is recursive.
+(@) Assume the following definitions:
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ trait I {
+ def factorial(x: Int): Int
+ }
+ class C extends I {
+ def factorial(x: Int) = if (x == 0) 1 else x * factorial(x - 1)
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\comment{
-For any index $i$ let $\fsig_i$ be a function signature consisting of a function
-name, an optional type parameter section, and zero or more parameter
-sections. Then a function declaration
-~\lstinline@def $\fsig_1 \commadots \fsig_n$: $T$@~
-is a shorthand for the sequence of function
-declarations ~\lstinline@def $\fsig_1$: $T$; ...; def $\fsig_n$: $T$@.
-A function definition ~\lstinline@def $\fsig_1 \commadots \fsig_n$ = $e$@~ is a
-shorthand for the sequence of function definitions
-~\lstinline@def $\fsig_1$ = $e$; ...; def $\fsig_n$ = $e$@.
-A function definition
-~\lstinline@def $\fsig_1 \commadots \fsig_n: T$ = $e$@~ is a shorthand for the
-sequence of function definitions
-~\lstinline@def $\fsig_1: T$ = $e$; ...; def $\fsig_n: T$ = $e$@.
-}
+ Here, it is OK to leave out the result type of `factorial`
+ in `C`, even though the method is recursive.
-\comment{
-\section{Overloaded Definitions}
-\label{sec:overloaded-defs}
-\todo{change}
-
-An overloaded definition is a set of $n > 1$ value or function
-definitions in the same statement sequence that define the same name,
-binding it to types ~\lstinline@$T_1 \commadots T_n$@, respectively.
-The individual definitions are called {\em alternatives}. Overloaded
-definitions may only appear in the statement sequence of a template.
-Alternatives always need to specify the type of the defined entity
-completely. It is an error if the types of two alternatives $T_i$ and
-$T_j$ have the same erasure (\sref{sec:erasure}).
-
-\todo{Say something about bridge methods.}
-%This must be a well-formed
-%overloaded type
-}
-\section{Import Clauses}
-\label{sec:import}
+Import Clauses
+--------------
-\syntax\begin{lstlisting}
- Import ::= `import' ImportExpr {`,' ImportExpr}
- ImportExpr ::= StableId `.' (id | `_' | ImportSelectors)
- ImportSelectors ::= `{' {ImportSelector `,'}
- (ImportSelector | `_') `}'
- ImportSelector ::= id [`=>' id | `=>' `_']
-\end{lstlisting}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+Import ::= import ImportExpr {‘,’ ImportExpr}
+ImportExpr ::= StableId ‘.’ (id | ‘_’ | ImportSelectors)
+ImportSelectors ::= ‘{’ {ImportSelector ‘,’}
+ (ImportSelector | ‘_’) ‘}’
+ImportSelector ::= id [‘=>’ id | ‘=>’ ‘_’]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-An import clause has the form ~\lstinline@import $p$.$I$@~ where $p$ is a stable
-identifier (\sref{sec:paths}) and $I$ is an import expression.
+An import clause has the form `import $p$.$I$` where $p$ is a
+[stable identifier](#paths) and $I$ is an import expression.
The import expression determines a set of names of importable members of $p$
which are made available without qualification. A member $m$ of $p$ is
-{\em importable} if it is not object-private (\sref{sec:modifiers}).
+_importable_ if it is not [object-private](#modifiers).
The most general form of an import expression is a list of {\em import
selectors}
-\begin{lstlisting}
-{ $x_1$ => $y_1 \commadots x_n$ => $y_n$, _ } .
-\end{lstlisting}
-for $n \geq 0$, where the final wildcard `\lstinline@_@' may be absent. It
-makes available each importable member \lstinline@$p$.$x_i$@ under the unqualified name
-$y_i$. I.e.\ every import selector ~\lstinline@$x_i$ => $y_i$@~ renames
-\lstinline@$p$.$x_i$@ to
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+{ $x_1$ => $y_1 , \ldots , x_n$ => $y_n$, _ }
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+for $n \geq 0$, where the final wildcard ‘_’ may be absent. It
+makes available each importable member `$p$.$x_i$` under the unqualified name
+$y_i$. I.e.\ every import selector `$x_i$ => $y_i$` renames
+`$p$.$x_i$` to
$y_i$. If a final wildcard is present, all importable members $z$ of
-$p$ other than ~\lstinline@$x_1 \commadots x_n,y_1 \commadots y_n$@~ are also made available
+$p$ other than `$x_1 , \ldots , x_n,y_1 , \ldots , y_n$` are also made available
under their own unqualified names.
Import selectors work in the same way for type and term members. For
-instance, an import clause ~\lstinline@import $p$.{$x$ => $y\,$}@~ renames the term
-name \lstinline@$p$.$x$@ to the term name $y$ and the type name \lstinline@$p$.$x$@
+instance, an import clause `import $p$.{$x$ => $y\,$}` renames the term
+name `$p$.$x$` to the term name $y$ and the type name `$p$.$x$`
to the type name $y$. At least one of these two names must
reference an importable member of $p$.
If the target in an import selector is a wildcard, the import selector
hides access to the source member. For instance, the import selector
-~\lstinline@$x$ => _@~ ``renames'' $x$ to the wildcard symbol (which is
+`$x$ => _` “renames $x$ to the wildcard symbol (which is
unaccessible as a name in user programs), and thereby effectively
prevents unqualified access to $x$. This is useful if there is a
final wildcard in the same import selector list, which imports all
@@ -902,34 +815,38 @@ whichever comes first.
Several shorthands exist. An import selector may be just a simple name
$x$. In this case, $x$ is imported without renaming, so the
-import selector is equivalent to ~\lstinline@$x$ => $x$@. Furthermore, it is
+import selector is equivalent to `$x$ => $x$`. Furthermore, it is
possible to replace the whole import selector list by a single
-identifier or wildcard. The import clause ~\lstinline@import $p$.$x$@~ is
-equivalent to ~\lstinline@import $p$.{$x\,$}@~, i.e.\ it makes available without
+identifier or wildcard. The import clause `import $p$.$x$` is
+equivalent to `import $p$.{$x\,$}`, i.e.\ it makes available without
qualification the member $x$ of $p$. The import clause
-~\lstinline@import $p$._@~ is equivalent to
-~\lstinline@import $p$.{_}@,
+`import $p$._` is equivalent to
+`import $p$.{_}`,
i.e.\ it makes available without qualification all members of $p$
-(this is analogous to ~\lstinline@import $p$.*@~ in Java).
+(this is analogous to `import $p$.*` in Java).
An import clause with multiple import expressions
-~\lstinline@import $p_1$.$I_1 \commadots p_n$.$I_n$@~ is interpreted as a
+`import $p_1$.$I_1 , \ldots , p_n$.$I_n$` is interpreted as a
sequence of import clauses
-~\lstinline@import $p_1$.$I_1$; $\ldots$; import $p_n$.$I_n$@.
+`import $p_1$.$I_1$; $\ldots$; import $p_n$.$I_n$`.
-\example Consider the object definition:
-\begin{lstlisting}
-object M {
- def z = 0, one = 1
- def add(x: Int, y: Int): Int = x + y
-}
-\end{lstlisting}
-Then the block
-\begin{lstlisting}
-{ import M.{one, z => zero, _}; add(zero, one) }
-\end{lstlisting}
-is equivalent to the block
-\begin{lstlisting}
-{ M.add(M.z, M.one) } .
-\end{lstlisting}
+(@) Consider the object definition:
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ object M {
+ def z = 0, one = 1
+ def add(x: Int, y: Int): Int = x + y
+ }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ Then the block
+
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ { import M.{one, z => zero, _}; add(zero, one) }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ is equivalent to the block
+
+ ~~~~~~~~~~~~~~~~~~~~~~ {.scala}
+ { M.add(M.z, M.one) }
+ ~~~~~~~~~~~~~~~~~~~~~~
View
24 README.md
@@ -17,6 +17,27 @@ General
Conversion from LaTeX - Guidelines
----------------------------------
+### Chapter conversion Checklist
+
+#. Convert all `\section{...}`
+#. Convert all `\subsection{...}`
+#. Convert all `\subsubsection{...}`
+#. Convert all `{\em ...}`
+#. Convert all `\lstlisting`
+#. Convert all `\lstinline`
+#. Convert all `\sref{sec:...}`
+#. Convert all `\begin{itemize}`
+#. Convert all `\begin{enumerate}`
+#. Convert all `\example`
+#. Convert all `\code`
+#. Convert all `\footnote`
+#. Convert all single quote pairs
+#. Convert all double quote pairs
+#. Look for manually defined enumerated lists (1. 2. 3. etc)
+#. Remove `%@M` comments
+#. Convert all extra macros (`\commadots`, etc)
+
+
### Code
Code blocks using the listings package of form
@@ -107,4 +128,5 @@ Finding rendering errors
------------------------
- MathJAX errors will appear within the rendered DOM as span elements with
- class `mtext` and style attribute `color: red` applied.
+ class `mtext` and style attribute `color: red` applied.
+
View
2  build.sh
@@ -5,8 +5,8 @@ cat 01-title.md \
03-lexical-syntax.md \
04-identifiers-names-and-scopes.md \
05-types.md \
+ 06-basic-declarations-and-definitions.md \
16-references.md > build/ScalaReference.md
-# 06-basic-declarations-and-definitions.md \
# 07-classes-and-objects.md \
# 08-expressions.md \
# 09-implicit-parameters-and-views.md \
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