<=就像你会“读”它:'小于或等于'。所以它是一个数学运算符，在<(小于?)、>(大于?)、==(等于?)、!=(不等于?)、<=(小于或等于?)和>=(大于或等于?)的列表中。

这不能与=>混淆，后者是一种右向双箭头，用于将参数列表与函数体分离，并将模式匹配中的测试条件(case块)与匹配发生时执行的函数体分离。你可以在我之前的两个回答中看到这样的例子。一、函数使用:

coll.map(tup => tup._2.reverse)

它已经被缩写为省略了类型。接下来的函数是

// function arguments         function body
(tup: Tuple2[Int, String]) => tup._2.reverse

与模式匹配使用:

def extract2(l: List[Int]) = l match {
   // if l matches Nil    return "empty"
   case Nil            => "empty"
   // etc.
   case ::(head, Nil)  => "exactly one element (" + head + ")"
   // etc.
   case ::(head, tail) => "more than one element"
}

只是为其他精彩的答案锦上添花。Scala提供了两个经常被批评的符号操作符，/:(foldLeft)和:\ (foldRight)操作符，第一个是右关联操作符。所以下面三个语句是等价的:

( 1 to 100 ).foldLeft( 0, _+_ )
( 1 to 100 )./:( 0 )( _+_ )
( 0 /: ( 1 to 100 ) )( _+_ )

就像下面这三个:

( 1 to 100 ).foldRight( 0, _+_ )
( 1 to 100 ).:\( 0 )( _+_ )
( ( 1 to 100 ) :\ 0 )( _+_ )

所以你想要一个详尽的答案?这里有一个有趣的，希望完整的，相当长的列表给你:)

http://jim-mcbeath.blogspot.com/2008/12/scala-operator-cheat-sheet.html

(免责声明-这篇文章写于2008年，所以可能有点过时)

!! AbstractActor
!! Actor // Sends msg to this actor and immediately ...
!! Proxy
! Actor // Sends msg to this actor (asynchronous).
! Channel // Sends a message to this Channel.
! OutputChannel // Sends msg to this ...
! Proxy // Sends msg to this ...
!= Any // o != arg0 is the same as !(o == (arg0)).
!= AnyRef
!= Boolean
!= Byte
!= Char
!= Double
!= Float
!= Int
!= Long
!= Short
!? AbstractActor
!? Actor // Sends msg to this actor and awaits reply ...
!? Channel // Sends a message to this Channel and ...
!? Proxy
% BigInt // Remainder of BigInts
% Byte
% Char
% Double
% Float
% Int
% Long
% Short
% Elem // Returns a new element with updated attributes, resolving namespace uris from this element's scope. ...
&&& Parsers.Parser
&& Boolean
&+ NodeBuffer // Append given object to this buffer, returns reference on this NodeBuffer ...
& BigInt // Bitwise and of BigInts
& Boolean
& Byte
& Char
& Enumeration.Set32 // Equivalent to * for bit sets. ...
& Enumeration.Set64 // Equivalent to * for bit sets. ...
& Enumeration.SetXX // Equivalent to * for bit sets. ...
& Int
& Long
& Short
&~ BigInt // Bitwise and-not of BigInts. Returns a BigInt whose value is (this & ~that).
&~ Enumeration.Set32 // Equivalent to - for bit sets. ...
&~ Enumeration.Set64 // Equivalent to - for bit sets. ...
&~ Enumeration.SetXX // Equivalent to - for bit sets. ...
>>> Byte
>>> Char
>>> Int
>>> Long
>>> Short
>> BigInt // (Signed) rightshift of BigInt
>> Byte
>> Char
>> Int
>> Long
>> Short
>> Parsers.Parser // Returns into(fq)
>> Parsers.Parser // Returns into(fq)
> BigDecimal // Greater-than comparison of BigDecimals
> BigInt // Greater-than comparison of BigInts
> Byte
> Char
> Double
> Float
> Int
> Long
> Ordered
> PartiallyOrdered
> Short
>= BigDecimal // Greater-than-or-equals comparison of BigDecimals
>= BigInt // Greater-than-or-equals comparison of BigInts
>= Byte
>= Char
>= Double
>= Float
>= Int
>= Long
>= Ordered
>= PartiallyOrdered
>= Short
<< BigInt // Leftshift of BigInt
<< Byte
<< Char
<< Int
<< Long
<< Short
<< Buffer // Send a message to this scriptable object.
<< BufferProxy // Send a message to this scriptable object.
<< Map // Send a message to this scriptable object.
<< MapProxy // Send a message to this scriptable object.
<< Scriptable // Send a message to this scriptable object.
<< Set // Send a message to this scriptable object.
<< SetProxy // Send a message to this scriptable object.
<< SynchronizedBuffer // Send a message to this scriptable object.
<< SynchronizedMap // Send a message to this scriptable object.
<< SynchronizedSet // Send a message to this scriptable object.
< BigDecimal // Less-than of BigDecimals
< BigInt // Less-than of BigInts
< Byte
< Char
< Double
< Float
< Int
< Long
< Ordered
< PartiallyOrdered
< Short
< OffsetPosition // Compare this position to another, by first comparing their line numbers, ...
< Position // Compare this position to another, by first comparing their line numbers, ...
<= BigDecimal // Less-than-or-equals comparison of BigDecimals
<= BigInt // Less-than-or-equals comparison of BigInts
<= Byte
<= Char
<= Double
<= Float
<= Int
<= Long
<= Ordered
<= PartiallyOrdered
<= Short
<~ Parsers.Parser // A parser combinator for sequential composition which keeps only the left result
** Enumeration.SetXX
** Set // Intersect. It computes an intersection with set that. ...
** Set // This method is an alias for intersect. ...
* BigDecimal // Multiplication of BigDecimals
* BigInt // Multiplication of BigInts
* Byte
* Char
* Double
* Float
* Int
* Long
* Short
* Set
* RichString // return n times the current string
* Parsers.Parser // Returns a parser that repeatedly parses what this parser parses, interleaved with the `sep' parser. ...
* Parsers.Parser // Returns a parser that repeatedly parses what this parser parses
* Parsers.Parser // Returns a parser that repeatedly parses what this parser parses, interleaved with the `sep' parser. ...
* Parsers.Parser // Returns a parser that repeatedly parses what this parser parses, interleaved with the `sep' parser.
* Parsers.Parser // Returns a parser that repeatedly parses what this parser parses
++: ArrayBuffer // Prepends a number of elements provided by an iterable object ...
++: Buffer // Prepends a number of elements provided by an iterable object ...
++: BufferProxy // Prepends a number of elements provided by an iterable object ...
++: SynchronizedBuffer // Prepends a number of elements provided by an iterable object ...
++ Array // Returns an array consisting of all elements of this array followed ...
++ Enumeration.SetXX
++ Iterable // Appends two iterable objects.
++ IterableProxy // Appends two iterable objects.
++ Iterator // Returns a new iterator that first yields the elements of this ...
++ List // Appends two list objects.
++ RandomAccessSeq // Appends two iterable objects.
++ RandomAccessSeqProxy // Appends two iterable objects.
++ Seq // Appends two iterable objects.
++ SeqProxy // Appends two iterable objects.
++ IntMap // Add a sequence of key/value pairs to this map.
++ LongMap // Add a sequence of key/value pairs to this map.
++ Map // Add a sequence of key/value pairs to this map.
++ Set // Add all the elements provided by an iterator ...
++ Set // Add all the elements provided by an iterator to the set.
++ SortedMap // Add a sequence of key/value pairs to this map.
++ SortedSet // Add all the elements provided by an iterator ...
++ Stack // Push all elements provided by the given iterable object onto ...
++ Stack // Push all elements provided by the given iterator object onto ...
++ TreeHashMap
++ TreeHashMap // Add a sequence of key/value pairs to this map.
++ Collection // Operator shortcut for addAll.
++ Set // Operator shortcut for addAll.
++ ArrayBuffer // Appends two iterable objects.
++ Buffer // Appends a number of elements provided by an iterable object ...
++ Buffer // Appends a number of elements provided by an iterator ...
++ Buffer // Appends two iterable objects.
++ BufferProxy // Appends a number of elements provided by an iterable object ...
++ Map // Add a sequence of key/value pairs to this map.
++ MapProxy // Add a sequence of key/value pairs to this map.
++ PriorityQueue
++ Set // Add all the elements provided by an iterator ...
++ SynchronizedBuffer // Appends a number of elements provided by an iterable object ...
++ RichString // Appends two iterable objects.
++ RichStringBuilder // Appends a number of elements provided by an iterable object ...
++ RichStringBuilder // Appends two iterable objects.
++= Map // Add a sequence of key/value pairs to this map.
++= MapWrapper // Add a sequence of key/value pairs to this map.
++= ArrayBuffer // Appends a number of elements in an array
++= ArrayBuffer // Appends a number of elements provided by an iterable object ...
++= ArrayStack // Pushes all the provided elements onto the stack.
++= Buffer // Appends a number of elements in an array
++= Buffer // Appends a number of elements provided by an iterable object ...
++= Buffer // Appends a number of elements provided by an iterator
++= BufferProxy // Appends a number of elements provided by an iterable object ...
++= Map // Add a sequence of key/value pairs to this map.
++= MapProxy // Add a sequence of key/value pairs to this map.
++= PriorityQueue // Adds all elements provided by an Iterable object ...
++= PriorityQueue // Adds all elements provided by an iterator into the priority queue.
++= PriorityQueueProxy // Adds all elements provided by an Iterable object ...
++= PriorityQueueProxy // Adds all elements provided by an iterator into the priority queue.
++= Queue // Adds all elements provided by an Iterable object ...
++= Queue // Adds all elements provided by an iterator ...
++= QueueProxy // Adds all elements provided by an Iterable object ...
++= QueueProxy // Adds all elements provided by an iterator ...
++= Set // Add all the elements provided by an iterator ...
++= SetProxy // Add all the elements provided by an iterator ...
++= Stack // Pushes all elements provided by an Iterable object ...
++= Stack // Pushes all elements provided by an iterator ...
++= StackProxy // Pushes all elements provided by an Iterable object ...
++= StackProxy // Pushes all elements provided by an iterator ...
++= SynchronizedBuffer // Appends a number of elements provided by an iterable object ...
++= SynchronizedMap // Add a sequence of key/value pairs to this map.
++= SynchronizedPriorityQueue // Adds all elements provided by an Iterable object ...
++= SynchronizedPriorityQueue // Adds all elements provided by an iterator into the priority queue.
++= SynchronizedQueue // Adds all elements provided by an Iterable object ...
++= SynchronizedQueue // Adds all elements provided by an iterator ...
++= SynchronizedSet // Add all the elements provided by an iterator ...
++= SynchronizedStack // Pushes all elements provided by an Iterable object ...
++= SynchronizedStack // Pushes all elements provided by an iterator ...
++= RichStringBuilder // Appends a number of elements provided by an iterable object ...
+: ArrayBuffer // Prepends a single element to this buffer and return ...
+: Buffer // Prepend a single element to this buffer and return ...
+: BufferProxy // Prepend a single element to this buffer and return ...
+: ListBuffer // Prepends a single element to this buffer. It takes constant ...
+: ObservableBuffer // Prepend a single element to this buffer and return ...
+: SynchronizedBuffer // Prepend a single element to this buffer and return ...
+: RichStringBuilder // Prepend a single element to this buffer and return ...
+: BufferWrapper // Prepend a single element to this buffer and return ...
+: RefBuffer // Prepend a single element to this buffer and return ...
+ BigDecimal // Addition of BigDecimals
+ BigInt // Addition of BigInts
+ Byte
+ Char
+ Double
+ Enumeration.SetXX // Create a new set with an additional element.
+ Float
+ Int
+ List
+ Long
+ Short
+ EmptySet // Create a new set with an additional element.
+ HashSet // Create a new set with an additional element.
+ ListSet.Node // This method creates a new set with an additional element.
+ ListSet // This method creates a new set with an additional element.
+ Map
+ Map // Add a key/value pair to this map.
+ Map // Add two or more key/value pairs to this map.
+ Queue // Creates a new queue with element added at the end ...
+ Queue // Returns a new queue with all all elements provided by ...
+ Set // Add two or more elements to this set.
+ Set // Create a new set with an additional element.
+ Set1 // Create a new set with an additional element.
+ Set2 // Create a new set with an additional element.
+ Set3 // Create a new set with an additional element.
+ Set4 // Create a new set with an additional element.
+ SortedMap // Add a key/value pair to this map.
+ SortedMap // Add two or more key/value pairs to this map.
+ SortedSet // Create a new set with an additional element.
+ Stack // Push all elements provided by the given iterable object onto ...
+ Stack // Push an element on the stack.
+ TreeSet // A new TreeSet with the entry added is returned,
+ Buffer // adds "a" from the collection. Useful for chaining.
+ Collection // adds "a" from the collection. Useful for chaining.
+ Map // Add a key/value pair to this map.
+ Set // adds "a" from the collection. Useful for chaining.
+ Buffer // Append a single element to this buffer and return ...
+ BufferProxy // Append a single element to this buffer and return ...
+ Map // Add a key/value pair to this map.
+ Map // Add two or more key/value pairs to this map.
+ MapProxy // Add a key/value pair to this map.
+ MapProxy // Add two or more key/value pairs to this map.
+ ObservableBuffer // Append a single element to this buffer and return ...
+ PriorityQueue
+ Set // Add a new element to the set.
+ Set // Add two or more elements to this set.
+ SynchronizedBuffer // Append a single element to this buffer and return ...
+ Parsers.Parser // Returns a parser that repeatedly (at least once) parses what this parser parses.
+ Parsers.Parser // Returns a parser that repeatedly (at least once) parses what this parser parses.
+= Collection // adds "a" from the collection.
+= Map // Add a key/value pair to this map.
+= ArrayBuffer // Appends a single element to this buffer and returns ...
+= ArrayStack // Alias for push.
+= BitSet // Sets i-th bit to true. ...
+= Buffer // Append a single element to this buffer.
+= BufferProxy // Append a single element to this buffer.
+= HashSet // Add a new element to the set.
+= ImmutableSetAdaptor // Add a new element to the set.
+= JavaSetAdaptor // Add a new element to the set.
+= LinkedHashSet // Add a new element to the set.
+= ListBuffer // Appends a single element to this buffer. It takes constant ...
+= Map // Add a key/value pair to this map.
+= Map // Add two or more key/value pairs to this map.
+= Map // This method defines syntactic sugar for adding or modifying ...
+= MapProxy // Add a key/value pair to this map.
+= MapProxy // Add two or more key/value pairs to this map.
+= ObservableSet // Add a new element to the set.
+= PriorityQueue // Add two or more elements to this set.
+= PriorityQueue // Inserts a single element into the priority queue.
+= PriorityQueueProxy // Inserts a single element into the priority queue.
+= Queue // Inserts a single element at the end of the queue.
+= QueueProxy // Inserts a single element at the end of the queue.
+= Set // Add a new element to the set.
+= Set // Add two or more elements to this set.
+= SetProxy // Add a new element to the set.
+= Stack // Pushes a single element on top of the stack.
+= StackProxy // Pushes a single element on top of the stack.
+= SynchronizedBuffer // Append a single element to this buffer.
+= SynchronizedMap // Add a key/value pair to this map.
+= SynchronizedMap // Add two or more key/value pairs to this map.
+= SynchronizedPriorityQueue // Inserts a single element into the priority queue.
+= SynchronizedQueue // Inserts a single element at the end of the queue.
+= SynchronizedSet // Add a new element to the set.
+= SynchronizedStack // Pushes a single element on top of the stack.
+= RichStringBuilder // Append a single element to this buffer.
+= Reactions // Add a reaction.
+= RefBuffer // Append a single element to this buffer.
+= CachedFileStorage // adds a node, setting this.dirty to true as a side effect
+= IndexedStorage // adds a node, setting this.dirty to true as a side effect
+= SetStorage // adds a node, setting this.dirty to true as a side effect
-> Map.MapTo
-> Map.MapTo
-- List // Computes the difference between this list and the given list ...
-- Map // Remove a sequence of keys from this map
-- Set // Remove all the elements provided by an iterator ...
-- SortedMap // Remove a sequence of keys from this map
-- MutableIterable // Operator shortcut for removeAll.
-- Set // Operator shortcut for removeAll.
-- Map // Remove a sequence of keys from this map
-- MapProxy // Remove a sequence of keys from this map
-- Set // Remove all the elements provided by an iterator ...
--= Map // Remove a sequence of keys from this map
--= MapProxy // Remove a sequence of keys from this map
--= Set // Remove all the elements provided by an iterator ...
--= SetProxy // Remove all the elements provided by an iterator ...
--= SynchronizedMap // Remove a sequence of keys from this map
--= SynchronizedSet // Remove all the elements provided by an iterator ...
- BigDecimal // Subtraction of BigDecimals
- BigInt // Subtraction of BigInts
- Byte
- Char
- Double
- Enumeration.SetXX // Remove a single element from a set.
- Float
- Int
- List // Computes the difference between this list and the given object ...
- Long
- Short
- EmptyMap // Remove a key from this map
- EmptySet // Remove a single element from a set.
- HashMap // Remove a key from this map
- HashSet // Remove a single element from a set.
- IntMap // Remove a key from this map
- ListMap.Node // Creates a new mapping without the given key. ...
- ListMap // This creates a new mapping without the given key. ...
- ListSet.Node // - can be used to remove a single element from ...
- ListSet // - can be used to remove a single element from ...
- LongMap // Remove a key from this map
- Map // Remove a key from this map
- Map // Remove two or more keys from this map
- Map1 // Remove a key from this map
- Map2 // Remove a key from this map
- Map3 // Remove a key from this map
- Map4 // Remove a key from this map
- Set // Remove a single element from a set.
- Set // Remove two or more elements from this set.
- Set1 // Remove a single element from a set.
- Set2 // Remove a single element from a set.
- Set3 // Remove a single element from a set.
- Set4 // Remove a single element from a set.
- SortedMap // Remove a key from this map
- SortedMap // Remove two or more keys from this map
- TreeHashMap // Remove a key from this map
- TreeMap // Remove a key from this map
- TreeSet // Remove a single element from a set.
- UnbalancedTreeMap.Node // Remove a key from this map
- UnbalancedTreeMap // Remove a key from this map
- Map // Remove a key from this map
- MutableIterable
- Set
- ListBuffer // Removes a single element from the buffer and return ...
- Map // Remove a key from this map
- Map // Remove two or more keys from this map
- MapProxy // Remove a key from this map
- MapProxy // Remove two or more keys from this map
- Set // Remove a new element from the set.
- Set // Remove two or more elements from this set.
-= Buffer // removes "a" from the collection.
-= Collection // removes "a" from the collection.
-= Map // Remove a key from this map, noop if key is not present.
-= BitSet // Clears the i-th bit.
-= Buffer // Removes a single element from this buffer, at its first occurrence. ...
-= HashMap // Remove a key from this map, noop if key is not present.
-= HashSet // Removes a single element from a set.
-= ImmutableMapAdaptor // Remove a key from this map, noop if key is not present.
-= ImmutableSetAdaptor // Removes a single element from a set.
-= JavaMapAdaptor // Remove a key from this map, noop if key is not present.
-= JavaSetAdaptor // Removes a single element from a set.
-= LinkedHashMap // Remove a key from this map, noop if key is not present.
-= LinkedHashSet // Removes a single element from a set.
-= ListBuffer // Remove a single element from this buffer. It takes linear time ...
-= Map // Remove a key from this map, noop if key is not present.
-= Map // Remove two or more keys from this map
-= MapProxy // Remove a key from this map, noop if key is not present.
-= MapProxy // Remove two or more keys from this map
-= ObservableMap // Remove a key from this map, noop if key is not present.
-= ObservableSet // Removes a single element from a set.
-= OpenHashMap // Remove a key from this map, noop if key is not present.
-= Set // Remove two or more elements from this set.
-= Set // Removes a single element from a set.
-= SetProxy // Removes a single element from a set.
-= SynchronizedMap // Remove a key from this map, noop if key is not present.
-= SynchronizedMap // Remove two or more keys from this map
-= SynchronizedSet // Removes a single element from a set.
-= Reactions // Remove the given reaction.
-= CachedFileStorage // removes a tree, setting this.dirty to true as a side effect
-= IndexedStorage // removes a tree, setting this.dirty to true as a side effect
/% BigInt // Returns a pair of two BigInts containing (this / that) and (this % that).
/: Iterable // Similar to foldLeft but can be used as ...
/: IterableProxy // Similar to foldLeft but can be used as ...
/: Iterator // Similar to foldLeft but can be used as ...
/ BigDecimal // Division of BigDecimals
/ BigInt // Division of BigInts
/ Byte
/ Char
/ Double
/ Float
/ Int
/ Long
/ Short
:/: Document
::: List
:: List
:: Document
:\ Iterable // An alias for foldRight. ...
:\ IterableProxy // An alias for foldRight. ...
:\ Iterator // An alias for foldRight. ...
== Any // o == arg0 is the same as o.equals(arg0).
== AnyRef // o == arg0 is the same as if (o eq null) arg0 eq null else o.equals(arg0).
== Boolean
== Byte
== Char
== Double
== Float
== Int
== Long
== Short
? Actor // Receives the next message from this actor's mailbox.
? Channel // Receives the next message from this Channel.
? InputChannel // Receives the next message from this Channel.
? Parsers.Parser // Returns a parser that optionally parses what this parser parses.
? Parsers.Parser // Returns a parser that optionally parses what this parser parses.
\ NodeSeq // Projection function. Similar to XPath, use this \ "foo"
\\ NodeSeq // projection function. Similar to XPath, use this \\ 'foo
^ BigInt // Bitwise exclusive-or of BigInts
^ Boolean
^ Byte
^ Char
^ Int
^ Long
^ Short
^? Parsers.Parser // A parser combinator for partial function application
^? Parsers.Parser // A parser combinator for partial function application
^^ Parsers.Parser // A parser combinator for function application
^^ Parsers.Parser // A parser combinator for function application
^^ Parsers.UnitParser // A parser combinator for function application
^^^ Parsers.Parser
| BigInt // Bitwise or of BigInts
| Boolean
| Byte
| Char
| Enumeration.Set32 // Equivalent to ++ for bit sets. Returns a set ...
| Enumeration.Set32 // Equivalent to + for bit sets. Returns a set ...
| Enumeration.Set64 // Equivalent to ++ for bit sets. Returns a set ...
| Enumeration.Set64 // Equivalent to + for bit sets. Returns a set ...
| Enumeration.SetXX // Equivalent to ++ for bit sets. Returns a set ...
| Enumeration.SetXX // Equivalent to + for bit sets. Returns a set ...
| Int
| Long
| Short
| Parsers.Parser // A parser combinator for alternative composition
| Parsers.Parser // A parser combinator for alternative composition
| Parsers.UnitParser // A parser combinator for alternative composition
|| Boolean
||| Parsers.Parser
||| Parsers.Parser // A parser combinator for alternative with longest match composition
||| Parsers.Parser // A parser combinator for alternative with longest match composition
||| Parsers.UnitParser // A parser combinator for alternative with longest match composition
~! Parsers.Parser // A parser combinator for non-back-tracking sequential composition
~! Parsers.Parser // A parser combinator for non-back-tracking sequential composition with a unit-parser
~! Parsers.Parser // A parser combinator for non-back-tracking sequential composition
~! Parsers.UnitParser // A parser combinator for non-back-tracking sequential composition with a unit-parser
~! Parsers.UnitParser // A parser combinator for non-back-tracking sequential composition
~> Parsers.Parser // A parser combinator for sequential composition which keeps only the right result
~ BigInt // Returns the bitwise complement of this BigNum
~ Parsers.OnceParser // A parser combinator for sequential composition
~ Parsers.Parser // A parser combinator for sequential composition
~ Parsers
~ Parsers.OnceParser // A parser combinator for sequential composition with a unit-parser
~ Parsers.OnceParser // A parser combinator for sequential composition
~ Parsers.Parser // A parser combinator for sequential composition with a unit-parser
~ Parsers.Parser // A parser combinator for sequential composition
~ Parsers.UnitOnceParser // A parser combinator for sequential composition with a unit-parser
~ Parsers.UnitOnceParser // A parser combinator for sequential composition
~ Parsers.UnitParser // A parser combinator for sequential composition with a unit-parser
~ Parsers.UnitParser // A parser combinator for sequential composition
unary_! Boolean
unary_+ Byte
unary_+ Char
unary_+ Double
unary_+ Float
unary_+ Int
unary_+ Long
unary_+ Short
unary_- BigDecimal // Returns a BigDecimal whose value is the negation of this BigDecimal
unary_- BigInt // Returns a BigInt whose value is the negation of this BigInt
unary_- Byte
unary_- Char
unary_- Double
unary_- Float
unary_- Int
unary_- Long
unary_- Short
unary_~ Byte
unary_~ Char
unary_~ Int
unary_~ Long
unary_~ Short

这里有很好的详尽的答案。

对我来说，关键的一点是，这有两类

op提到的符号是scala sdk中的函数名。在scala中，使用这些字符(包括unicode字符)来编写函数名是合法的。这将是一个很长的列表，试图从sdk中提到所有已经在其他答案中提到的问题

还有一些符号不是函数名，而是语言语法本身的一部分，如=>，_或操作符，如&&，||等。

Scala和其他语言的一个(在我看来是好的)区别是，它允许你用几乎任何字符来命名你的方法。

您列举的不是“标点符号”，而是简单明了的方法，因此它们的行为因对象而异(尽管存在一些约定)。

例如，查看Scaladoc文档中的List，您将看到这里提到的一些方法。

请记住以下几点:

大多数情况下，A操作符+= B组合转换为A = A操作符B，如||=或++=示例。 以:结尾的方法是右结合的，这意味着A:: B实际上是B.::(A)。

您可以通过浏览Scala文档找到大部分答案。在这里保留一个参考将重复工作，并且它将很快落后:)

我认为现代IDE对于理解大型scala项目至关重要。由于这些操作符也是方法，在intellij思想中，我只是控制-单击或控制-b进入定义。

你可以右键点击一个cons操作符(::)，然后在scala javadoc中说“在这个列表的开头添加一个元素”。在用户定义的操作符中，这一点变得更加关键，因为它们可能被定义为很难找到的隐式…你的IDE知道隐式的定义在哪里。