What does the symbol mean in Haskell?

53. The @ Symbol is used to both give a name to a parameter and match that parameter against a pattern that follows the @ . It’s not specific to lists and can also be used with other data structures.

What does AT symbol do in Haskell?

In Haskell, it is used in so-called as-patterns. This notation can be used to give aliases to patterns, making them more readable.

What does [] mean in Haskell?

[] – Empty list. “abc” – List of three characters (strings are lists). • ‘a’ : ‘b’ : ‘c’ : [] – List of characters (same as “abc”).

What does >> mean in Haskell?

Sevan Golnazarian. 550●7 ●16. Up vote 5. I’m no Haskell expert, but >> is an operator that is used for working with monads, which are an unusual feature that (among many other things) enable imperative-style programming in Haskell.

What does colon mean in Haskell?

In Haskell, the colon operator is used to create lists (we’ll talk more about this soon). This right-hand side says that the value of makeList is the element 1 stuck on to the beginning of the value of makeList .

What is semicolon Haskell?

In Haskell, the semicolon still exists, but it’s an optional syntactic construct that when combiend with the brace {} syntax, they replace significant whitespace. let {a = 1; b = 2;} in a + b . This way you can use significant whitespace when it’s appropriate, and when it’s not, you don’t need it.

What is backslash in Haskell?

Anonymous Functions – lambdas The backslash is used as the nearest ASCII equivalent to the Greek letter lambda (λ). Note: Since lambdas are a special character in Haskell, the \ on its own will be treated as the function and whatever non-space character is next will be the variable for the first argument.

What does ++ mean in Haskell?

The ++ operator is the list concatenation operator which takes two lists as operands and “combine” them into a single list.

What does backslash mean in Haskell?

What do the arrows mean in Haskell?

0. I think it is called the arrow. According to “Real World Haskell” : -> has only one meaning: it denotes a function that takes an argument of the type on the left and returns a value of the type on the right.

What does double colon mean in Haskell?

It means has type, so run has type Int -> Int -> Int. How comes you think you can read Haskell programs without even knowing basic language concepts, symbols and notions? Sometimes it is a good idea to read a language reference, and Haskell has a really good one.

What does concat do in Haskell?

concat flattens a list of lists into just a list of elements. It will just remove one level of nesting.

What are as-patterns in Haskell?

To add to what the other people have said, they are called as-patterns (in ML the syntax uses the keyword “as”), and are described in the section of the Haskell Report on patterns. Thanks for contributing an answer to Stack Overflow!

What is the use of @ symbol in a list parameter?

The @ Symbol is used to both give a name to a parameter and match that parameter against a pattern that follows the @. It’s not specific to lists and can also be used with other data structures. This is useful if you want to “decompose” a parameter into it’s parts while still needing the parameter as a whole somewhere in your function.

What is the use of the @ symbol in constructor?

Without the @, you’d have to choose between (1) or (2): (3). This syntax actually works for any constructor; if you have data Tree a = Tree a [Tree a], then t@ (Tree _ kids) gives you access to both the tree and its children. The @ Symbol is used to both give a name to a parameter and match that parameter against a pattern that follows the @.