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hackage.haskell.org › package › base › docs › Data-Char.html

Data.Char - Hackage - Haskell

Read a string representation of a character, using Haskell source-language escape conventions, and convert it to the character that it encodes.

hackage.haskell.org › package › haskell98 › docs › Char.html

Char - Hackage - Haskell

The character type Char is an enumeration whose values represent Unicode (or equivalently ISO/IEC 10646) characters (see http://www.unicode.org/ for details). This set extends the ISO 8859-1 (Latin-1) character set (the first 256 characters), which is itself an extension of the ASCII character ...

Discussions

What is the difference between [[Char]] and [Char] in Haskell? - Stack Overflow

If all you want to do is reverse a single string, the type would be [Char] -> [Char]. This function reverses each string in a list of strings. More on stackoverflow.com

stackoverflow.com

If a string is a list of characters, then why doesn't this work?

I think the type of “ERIC” is [Char] and the type of ["E","R","I","C"] is [[Char]]. On the other hand, the type of [‘E’, ‘R’, ‘I’, ‘C’] is [Char]. This is because Haskell uses double quotes to indicate String literals and single quotes to indicate Char literals. More on reddit.com

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November 12, 2021

get first char of a String

Instead of having a fervent safety debate (already thoroughly covered)... this might help you. Prelude> take 1 "hello" "h" Prelude> take 1 "" "" Prelude> head "hello" 'h' Prelude> head "" *** Exception: Prelude.head: empty list More on reddit.com

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October 18, 2012

plutus pioneer program - Is type String truly equal to type [Char], and is Haskell truly "pure"? - Cardano Stack Exchange

One fundamental of Haskell is that a string is really a list of characters. More on cardano.stackexchange.com

cardano.stackexchange.com

February 13, 2022

Haskell

haskell.org › hugs › pages › libraries › base › Data-Char.html

stackoverflow.com › questions › 55124206 › what-is-the-difference-between-char-and-char-in-haskell

The character type Char is an enumeration whose values represent Unicode (or equivalently ISO/IEC 10646) characters (see http://www.unicode.org/ for details). This set extends the ISO 8859-1 (Latin-1) character set (the first 256 charachers), which is itself an extension of the ASCII character ...

Stack Overflow

What is the difference between [[Char]] and [Char] in Haskell? - Stack Overflow

downloads.haskell.org › ~ghc › 6.0 › docs › html › base › Data.Char.html

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'a' is a Char, a single character.

['a','b','c'] is a string, a list-of-Char. This list can also be written as "abc", using double quotes. Its type can be written as String or [Char].

["abc", "de"] is a list of strings. Its type can be written as [String] or [[Char]] (list-of-lists-of-Char).

We could go on, and say that [["abc","de"], ["ef", "abc"]] is a [[String]] (list-of-lists-of-strings) or [[[Char]]].

Your revStr takes as input not a single string, but a list of strings, hence the [[Char]] type. Its output is again a list of strings.

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Char is a character, meaning a single symbol like 'A', '$' or '3'
[Char] is a list of characters, also called a String (note [Char] = String) like ['A','$','3'] = "A$3"
[[Char]] is a list of lists of characters, (also [[Char]] = [String]). This is essentially a list of Strings like ["Hello", "World"]

revStr reverses all Strings (or [Char]) in the provided List, thus its type is a list of Strings

Haskell

reddit.com › r/haskell › if a string is a list of characters, then why doesn't this work?

The character type Char is an enumeration whose values represent Unicode characters. A character literal in Haskell has type Char · To convert a Char to or from an Int, use toEnum and fromEnum from the Enum class respectively (equivalently ord and chr also do the trick)

r/haskell on Reddit: If a string is a list of characters, then why doesn't this work?

November 12, 2021 -

All the code is here (https://github.com/djotaku/adventofcode/blob/800175cb4e0a69cb8d15e88d0727a07e7108fd8d/2016/Day_02/Haskell/solution.hs) if you need to understand what's in findNextNumber, but basically, I have this function:

findNumberRow number directionList = foldl findNextNumber number directionList

If I feed it:

findNumberRow 4 ["R", "L"]

I get the right answer. But if I feed it:

findNumberRow 4 "RL"

I get:

error:

• Couldn't match type ‘Char’ with ‘[Char]’ Expected type: [[Char]] Actual type: [Char] • In the second argument of ‘findNumberRow’, namely ‘"RL"’ In the expression: findNumberRow 4 "RL" In an equation for ‘it’: it = findNumberRow 4 "RL"

Why? I thought "ERIC" was equal to ["E","R","I","C"] in Haskell.

I think the type of “ERIC” is [Char] and the type of ["E","R","I","C"] is [[Char]]. On the other hand, the type of [‘E’, ‘R’, ‘I’, ‘C’] is [Char]. This is because Haskell uses double quotes to indicate String literals and single quotes to indicate Char literals.

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What you are feeding it in your first example (findNumberRow 4 ["R", "L"]) is a [String]/[[Char]] a list of Strings, while in your second example (findNumberRow 4 "RL") you are trying to feed it just a String. Haskell uses single quotes (') to denote a Char so... ["R","L"] = [['R'],['L']] "RL" = ['R','L'] "ERIC" = ['E','R','I','C'].

W3cubDocs

docs.w3cub.com › haskell~7 › libraries › base-4.8.2.0 › data-char

Data.Char - Haskell 7 - W3cubDocs

The character type Char is an enumeration whose values represent Unicode (or equivalently ISO/IEC 10646) characters (see http://www.unicode.org/ for details). This set extends the ISO 8859-1 (Latin-1) character set (the first 256 characters), which is itself an extension of the ASCII character ...

Uni-freiburg

www2.informatik.uni-freiburg.de › ~thiemann › haskell › haskell98-library-html › char.html

The Haskell 98 Library Report: Character Utilities

The function showLitChar converts a character to a string using only printable characters, using Haskell source-language escape conventions. The function lexLitChar does the reverse, returning the sequence of characters that encode the character. The function readLitChar does the same, but in addition converts the to the character that it encodes.

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hackage.haskell.org › package › base-4.3.1.0 › docs › Data-Char.html

Data.Char - Hackage - Haskell.org

The character type Char is an enumeration whose values represent Unicode (or equivalently ISO/IEC 10646) characters (see http://www.unicode.org/ for details). This set extends the ISO 8859-1 (Latin-1) character set (the first 256 charachers), which is itself an extension of the ASCII character ...

hackage.haskell.org › package › haskell2020 › docs › Data-Char.html

web.cs.dal.ca › ~nzeh › Teaching › 3137 › haskell › first_steps › basic_types › strings

The character type Char is an enumeration whose values represent Unicode (or equivalently ISO/IEC 10646) code points (i.e. characters, see http://www.unicode.org/ for details). This set extends the ISO 8859-1 (Latin-1) character set (the first 256 characters), which is itself an extension of ...

Dal University

Characters and Strings - CSCI 3137: Haskell Programming

The character type in Haskell is Char. Whereas in C and C++, characters are 8-bit characters, representing the extended ASCII character set, Haskell's characters are unicode characters, as in most modern programming languages.

Educative

educative.io › answers › how-to-get-the-first-char-from-a-string-in-haskell

How to get the first char from a string in Haskell

We can use the take function provided by Haskell to get the first character from a string.

reddit.com › r/haskell › get first char of a string

r/haskell on Reddit: get first char of a String

October 18, 2012 -

Hey there Im new with Haskell, for a function i need to get the first char out of a String, any Idea how i could do this?

Instead of having a fervent safety debate (already thoroughly covered)... this might help you. Prelude> take 1 "hello" "h" Prelude> take 1 "" "" Prelude> head "hello" 'h' Prelude> head "" *** Exception: Prelude.head: empty list

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Important to note: head is unsafe if the string might not have a first character. Control.Error exports a safe version :)

Real World Haskell

book.realworldhaskell.org › read › characters-strings-and-escaping-rules.html

Appendix B. Characters, strings, and escaping rules

Haskell's escaping rules follow the pattern established by the C programming language, but expand considerably upon them. A single character is surrounded by ASCII single quotes, ', and has type Char.

Stack Exchange

cardano.stackexchange.com › questions › 7199 › is-type-string-truly-equal-to-type-char-and-is-haskell-truly-pure

plutus pioneer program - Is type String truly equal to type [Char], and is Haskell truly "pure"? - Cardano Stack Exchange

hackage-content.haskell.org › package › base-4.22.0.0 › docs › Data-Char.html

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Somewhere in the Haskell based libraries String is defined as a type alias as:

type String = [Char]

The problem with your function is that GHC is not able to determine the type of "aeiou". In this case you would need to add a type signature like this (untested but should work):

vowelz :: Char -> Bool
vowelz a
    | a `elem` vowels = True
    | otherwise = False
   where
     vowels :: String
     vowels = ['a','e','i','o','u']

Haskell

Read a string representation of a character, using Haskell source-language escape conventions, and convert it to the character that it encodes.

hackage.haskell.org › package › base-4.7.0.1 › docs › Data-Char.html

Data.Char - Hackage

The character type Char is an enumeration whose values represent Unicode (or equivalently ISO/IEC 10646) characters (see http://www.unicode.org/ for details). This set extends the ISO 8859-1 (Latin-1) character set (the first 256 characters), which is itself an extension of the ASCII character ...