Bool Function In Dart Bool is typically used as a wrapper class for boolean values in situations where nullability needs to be explicitly declared, The only real example is converting a callable object to a function (by tearing off the call method), which is done implicitly if the context requires a function, Oct 31, 2019 · 3 I'm a Java developer and the newbie in Dart, Feb 12, 2025 · Dart is an object-oriented language with classes and mixin-based inheritance, h (which expectedly resolves to _Bool), The return statements are for the function you're passing to the forEach method, not for the isGuessInWord function, Feb 9, 2023 · The analyzer claims: error: Conditions must have a static type of 'bool', Often Dart's control flow analysis can detect when a non-nullable variable is set to a non-null value before it's used, but sometimes analysis fails, dev/guides/language/language-tour#functions): Nov 26, 2024 · Assertions are powerful tools in a developer's arsenal, helping to identify and prevent bugs early in the development process, Learn about the dart boolean and the Bool class, Function type of return Future value, Nov 12, 2025 · Although you could detect initialization by storing the state in a late variable and having a separate boolean field that tracks whether the variable has been set, that's redundant because Dart internally maintains the initialized status of the late variable, Feb 14, 2019 · The return type returned from doesNameAlreadyExist is Future<bool>, so the line doesNameAlreadyExist("userName", usernameController, If you intend for a list to contain only strings, you can declare it as List<String> (read that as "list of string"), These are the reserved words in Dart, Dec 4, 2025 · bool isPalindrome(String text) => text == text, 10 is taking off with dot shorthands, stable build hooks, nuanced deprecation annotations, and more! Learn more API docs for the List class from the dart:core library, for the Dart programming language, bool operator == ( Object other ) The equality operator, , HasValue Jul 5, 2011 · Can there ever be a bool with a value of 0x2 or is that prohibited by the standard (or even a meaningless question)? Learn Dart Boolean inbuilt dart data types that can store true and false values with examples conditional expressions, if and switch statements, Mar 11, 2024 · Flutter setup suddenly broken down, Aug 2, 2021 · I'm Using GetX Package for State Management in Flutter, but instead of bring the value from the function it ke API docs for the listEquals function from the foundation library, for the Dart programming language, Variables - Variables store values and can be used in expressions In the Dart programming language, bool is a supported data type, which only includes 2 values, true and false, The table shows Dart's operator associativity and operator precedence from highest to lowest, which are an approximation of Dart's operator relationships, API docs for the expect function from the expect library, for the Dart programming language, Even with a default value, someone can explicitly pass null as argument, As such, you should treat JS values as foreign types, Introduction to the Dart if statement # An if statement allows you to do something only if a condition is true, For example, the bitwise operators truncate their operands to 32-bit integers when compiled to JavaScript, (non_bool_condition at [experiments] lib/patterns, Nov 13, 2025 · Lazily initializing a variable, Feb 27, 2024 · I was setting up firebase for my flutter app follow this tut: https://firebase, I have tried to typecast as follows that resolves the issue: But I need a way to provide either of the class as an argument instead of a single base class, PREFER starting a boolean variable or property comment with "Whether" followed by a noun or gerund phrase, Hi! I'm writing a function that I want to use to check if a object already exist in firestore, but I'm having trouble with the execution order and I don't know where I'm going wrong, trim(); final docRef = _db, Functions sizeOf <T extends SizedNativeType>() → int Number of bytes used by native type T, Aug 27, 2025 · Dart values and JS values belong to separate language domains, That's not great, pop() has a return type of Future<void>, you can't return this from your onBackPressed function Jan 10, 2025 · In Dart, functions and methods typically accept arguments in a predefined order, The matching elements have the same order in the returned iterable as they have in iterator, dart:330) The function ( (a) => b) is highlighted, I think that what you try to achieve is: They are supported directly in the language through async and async* functions, and are available to all libraries through the dart:core library, Nov 4, 2025 · Extension methods add functionality to existing libraries, I'm trying to show data based on whether condition is true or not, A Stream is a way to get a sequence of values, such as events, The keyword bool is used to represent a Boolean literal in DART, Value or x, The function then Feb 28, 2021 · Dart language provides a pre-defined data type called boolean which can store two possible values, either true or false, ValueGetter is an anonymous function that returns a value, which you provide for someone who wants to get it, Logical operators !, ||, and && can be used, Only expressions can appear between the arrow (=>) and the semicolon (;), I have tried with: () {} - A value of type 'Null Function ( )' can't be assigned to a variable of type 'dynamic Function (bool)', In C++, why is the bool type 8 bits long (on my system)? Only one bit is enough to hold the Boolean value, Aug 7, 2025 · To construct and provide types for JS values, you use and declare interop types, which also contain interop members, May 5, 2023 · The main difference between Bool and bool is that Bool is not a native type in Dart, while bool is a native type, For example, when you use code completion in an IDE, it suggests extension methods alongside regular methods, If you want to be absolutely certain that the value is not null, you must guard all ways to set the value, bool objectExists(String object, String collection) { final String objectParsed = object, == indeed accepts a non-nullable Object as an argument, In Dart and Flutter, callbacks are used extensively for handling asynchronous operations, user interactions, and more, The async and await keywords support asynchronous programming, letting you write asynchronous code that looks similar to synchronous code, org Oct 22, 2025 · Everything about functions in Dart, Iterating will not cache API docs for the bool class from the dart:core library, for the Dart programming language, API documentation is available in the dart:ffi API reference, Unlike other collection types, records are fixed-sized, heterogeneous, and typed, Apr 22, 2021 · void showOverlay({@required BuildContext context, @required String text, @required bool successful, VoidCallback finished}) {} and dart is complaining becuase named parameters is best practice as mentioned in dart docs Positional boolean parameters are a bad practice because they are very ambiguous, Object, VM dart:ffi Foreign Function Interface for interoperability with the C programming language, How can we implement if we want to do deep equal? What is the good way to override hashCode and == operator? Sep 25, 2018 · I call the functions in the main, You can use generics to reduce code duplication, Oct 15, 2025 · Dart supports the operators shown in the following table, Jun 16, 2021 · the problem is the header , Basically it boils down to dart not calling extension methods on receives of one of the following three types: dynamic, Never, or void as stated here, Dart provides various operators that work with boolean values, including logical and comparison operators, As long as the returned Iterable is not iterated over, the supplied function test will not be invoked, API docs for the intToBool function from the numdart library, for the Dart programming language, split(''), I have a function that checks if a document exists or not on Firestore Nov 17, 2023 · Expressions in Dart are constructs that evaluate to a single value, The overriding method must still be an equivalence relation, h header is an indication that your code is OK with the identifier bool being 'reserved', i, h, Sep 25, 2008 · 2 bool is a primitive type, meaning that the value (true/false in this case) is stored directly in the variable, Boolean is an object, updateItem("item1", 7, To declare a boolean variable in Dart programming language, the keyword bool is used, fromCharCode(c); Feb 7, 2012 · Dart has a true boolean type named bool, with only two values: true and false (and, I suppose, null), Dec 4, 2025 · API docs for the Function class from the dart:core library, for the Dart programming language, Feb 12, 2025 · Dart supports if statements with optional else clauses, Can't use an expression of type 'bool Function (K)?' as a function because potentially null Asked 1 year, 9 months ago Modified 1 year, 9 months ago Viewed 157 times May 27, 2021 · The argument type 'bool Function(EmployeeDetails)' can't be assigned to the parameter type 'bool Function(SalesDetails)?', collection(collection), So you have to assign the result in order to negate, The components of an expression in Dart are: Literals - These are values written directly in the code like string literals, numeric literals, boolean literals, list literals, map literals, etc, Feb 19, 2021 · Before posting I took at look at previous questions (because there are many) but I didn't find something that suited my needs, Dec 4, 2025 · Iterable <E> where ( bool test( E element ) ) Creates a new lazy Iterable with all elements that satisfy the predicate test, Oct 3, 2018 · The explanation for this can be found here: first one by Erik, a dart maintainer @Google and the second by a community member, To pass Dart values like a List or Function to interop members or convert from JS values to Dart values, you use conversion functions unless the interop member contains a primitive type, In the previous example, _nobleGases[atomicNumber] != null; returns a boolean value, Setting a bool to none gives it a third state akin to undecided, Like this: Dart comes with a 'Boolean' datatype for variables, The fileContains function is marked with async right before its body, which means that you can use await inside it, and that it must return a future, Expressions evaluate to values, The only real difference is storage, This blog will explore the intricacies of Dart assert statements, their practical applications, and best practices for effective usage in your error: The argument type 'void Function (bool)' can't be assigned to the parameter type 'void Function (bool?)' Issue the problem is the header , Dart provides an inbuilt support for the Boolean data type, Since SystemNavigator, isDialogOpen! \\ this means you are sure a null can't be returned 2- So handle the null case and pass what's appropriate to the function from auth, Apr 3, 2025 · The dart boolean is a data type that holds two values - true or false, The function type looks like bool to me, You are allowed to have return e; statements, but only if the type of e is void, Null or dynamic, Here is some examples: bool BodyNode::isCollidable() const void BodyNode::setCollidability(bool _isCollidable) bool BodyNode::depends Sep 4, 2025 · Learn to use the Dart language and libraries, The return type is Object? because onFalse and onTrue can potentially return different types, Due to Dart's boolean conversion rules, all values except true are converted to false, How can I compare two objects to be the same like Java without be preparing this code below? Sep 16, 2025 · A library to parse and evaluate simple dart and javascript like expressions, Like other collection types, they let you bundle multiple objects into a single object, Override this method to specify a different equality relation on a class, Other terms for similar functionality include native interface and language bindings, To learn more about configuring the types collections contain, check out Generics, You could change the forEach to be a standard for , You can implement many of these operators as class members, This arrow syntax is a way to define a function that executes the expression to its right and returns its value, Aug 26, 2021 · bool tick() => !_tick; _tick should be defined, and this function will return negated value, PREFER starting comments of a function or method with third-person verbs if its main purpose is a side effect, Useful for Anti DDos, every time the user Aug 13, 2021 · I'm storing a bool value in shared preferences and getting the bool data using the future<bool> method in the main, For example, consider this call to the List class's any() method: Oct 22, 2025 · Everything about functions in Dart, In the original example the bold variable was public and not final, which means that you must also guard the setter, dart:isolate Concurrent programming using isolates: independent workers that are similar to threads but don't share memory, communicating only via messages, May 20, 2011 · How do you convert a nullable bool? to bool in C#? I have tried x, Sep 19, 2024 · Press enter or click to view image in full size When preparing for a technical interview, understanding how Dart handles data passing in functions — whether by value or reference — is crucial Dec 22, 2023 · When I run it, I get the error: "The return type ‘bool Function ()’ isn’t a ‘bool’, as required by the closure’s context, API docs for the BoolCallBack typedef from the m_callback library, for the Dart programming language, For example, here's a regular expression that matches a substring containing one or more digits: var numbers = RegExp (r'\d+'); Jan 13, 2022 · How to set all data of List<bool> to be false with some function Asked 3 years, 11 months ago Modified 3 years, 11 months ago Viewed 8k times Aug 9, 2019 · I want check if device is connected to internet or not and i done with class that do this work and return to me a bool value and i use from this class to other page and pass returned value to bool I have a future bool method and i want to use this method IconButton color, Importantly Dec 30, 2022 · The onWillPop configuration of WillPopScope requires a function with return type Future<bool>, and depending on the return value the pop will be either executed or not, see here: If the callback returns a Future that resolves to false, the enclosing route will not be popped, To interact with these asynchronous results, you can use the async and await keywords, To provide Dart types for JS values, dart:js_interop exposes a set of types prefixed with JS called "JS types", Basically, including the stdbool, in statement so the return s are not inside an function: bool isGuessInWord(String guess, String word) { for (final c in word, But gets this error which says `type 'bool Nov 4, 2025 · Besides showing an anonymous function (the argument to where()), this code shows that you can use a function as an argument: the top-level print() function is an argument to forEach(), This post explores callback functions, their usage, and provides practical examples in Dart and Flutter, readAsString method from dart:io is an asynchronous function returning a Future<String>, See full list on darttutorial, dart(argument_type_not_assignable), You might use extension methods without even knowing it, Compilation environment declarations specify configuration options as key-value pairs that are accessed and evaluated at compile time, The parameter should be optional, Sep 4, 2025 · AVOID redundancy with the surrounding context, Every object is an instance of a class, and all classes except Null descend from Object, Jun 22, 2021 · Because of function having bool statement i have used Function(bool?) here Widget buildSwitchtile(String title, String desc, bool currentvalue, Function(bool?) updatevalue) { ret May 5, 2025 · Asynchronous programming often uses callback functions, but Dart provides alternatives: Future and Stream objects, I found a discussion about it (paragraph "Passing value types by reference") here: value types in Dart, but I still wonder if there The isTextFile() function returns a value of the bool? type not bool, 5); Oct 18, 2025 · Arrow syntax You might have seen the => symbol in Dart code, Records are real values; you can store them in variables, nest them, pass them to and from functions, and store them in data structures such as lists, maps, and sets, They are the most basic units of the Dart programming language, It doesn't take arguments Jun 16, 2020 · I've got this error and I don't know how to deal with it: A value of type 'Future<bool>' can't be assigned to a variable of type 'bool' My code looks like this: Everything about functions in Dart, The function then Aug 7, 2025 · You can specify compilation environment declarations when building or running a Dart application, And then some, Dec 19, 2024 · Understanding Function Pointers in Flutter Function Pointers in Dart What is a Function Pointer? A function pointer means passing a function as an argument to another function, just like how we Feb 22, 2022 · 1 I wrote short flutter app that have a async function that get value from cloud firestore and return Future bool type according to the information from the database, Im trying to build the todoye app and as you can see the call back is considered ValueChanged<bool?> not a simple function so i cant move my logic to a another Feb 9, 2023 · However, using the function like this throws an error at the function call that The return type 'Set<bool>' isn't a 'bool', as required by the closure's context, Aug 23, 2022 · I already have initialise the bool variable then create a function and add it to my init state so as soon as the app loads it fetch the value, Read more about functions in Dart, including optional parameters, default parameter values, and lexical scope, May 21, 2019 · This guide shows you how to create, run, handle errors and execute multiple futures in Flutter, reversed, Oct 18, 2025 · To accommodate that initial asynchrony, other plain Dart functions also need to become asynchronous, It always showAlert "OK", i think the problem is the the utility class checkConnection () returns a future bool type, Mixin-based inheritance means that although every class (except for the top class, Object?) has exactly one superclass, a class body can be reused in multiple class hierarchies, May 5, 2025 · A deep dive into Dart language and library changes related to null safety, Dec 4, 2025 · API docs for the operator & method from the bool class, for the Dart programming language, void functionInWhen (Ob Dec 4, 2025 · API docs for the tryParse method from the bool class, for the Dart programming language, If i use below codes, i see a error message on my device screen type'Future' is not a subtype of type 'bool' in type of cast, Except for default constructors, these functions use the same name as their class, The naming for Boolean functions is not consistent in DART now, Jun 4, 2025 · The bool type is commonly used in conditional statements, loops, and logical expressions, toLowerCase(), dart file, dart file but it has problems, For example, you could use a conditional expression but not an if statement, A total ordering on a type means that for two values, either they are equal or one is greater than the other (and the latter must then be smaller than the former), A Future is like a promise for a result to be provided sometime in the future, Objects of type _Bool hold either 0 or 1, while true and false are also macros from stdbool, A comparison function represents an ordering on a type of objects, For more information about the analyzer, see Customizing static analysis, com/docs/flutter/setup?hl=vi&platform=android when i run "dart pub global activate flutterfire_cli", it went error, It should never Jul 3, 2025 · Generics are often required for type safety, but they have more benefits than just allowing your code to run: Properly specifying generic types results in better generated code, It is a bit strange that Reference would expand that parameter type to be Object?, Example with final variable: Jun 18, 2025 · Dart has built-in support for list, set, and map collections, bool? can contain three different values: true, false and null, The function then Sep 15, 2025 · The Dart language is type safe: it uses a combination of static type checking and runtime checks to ensure that a variable's value always matches the variable's static type, sometimes referred to as sound typing, One benefit of static type checking is the ability to find bugs at compile time using Dart's Dec 4, 2025 · API docs for the parse method from the bool class, for the Dart programming language, In C99 the native type is actually called _Bool, while bool is a standard library macro defined in stdbool, Jul 26, 2021 · Get, inherited listenAndPump (void onData(bool event), {Function? onError, void onDone()?, bool? cancelOnError}) → StreamSubscription <bool> Returns a StreamSubscription similar to listen, but with the added benefit that it primes the stream with the current value, rather than waiting for the next value, What is a Callback Comparator<T> typedef Comparator <T> = int Function(T a, T b) The signature of a generic comparison function, " I tried checking and reading the documentation but I still don’t get what exactly is wrong…does someone have an idea? BoolCallBack = void Function(bool value) Bool BoolCallBackFuture <T> = Future <T> Function(bool value) BoolCallBackReturn <T> = T Function(bool value) BoolCallbackWithInt = bool Function(int value) CallBack = dynamic Function(dynamic value) CallBack FutureCallback <T> = Future <T> Function() General, dart:io File, socket, HTTP, and other I/O support for non-web applications, You need to await, or then the result, The value of Boolean is either true or false, doc Sep 4, 2025 · Learn about type aliases in Dart, Typedefs Dart_NativeMessageHandler = Void Function(Int64, Pointer <Dart_CObject>) NativeFinalizerFunction = NativeFunction <Void Function(Pointer <Void> token)> The native function type for NativeFinalizer s, Dec 4, 2025 · Functions sizeOf <T extends SizedNativeType>() → int Number of bytes used by native type T, Future<bool> _onWillPop() async{ After this, you will just need to return a boolean value whenever your method completes its processing just like any other function Feb 12, 2025 · Everything you wanted to know about handling errors and exceptions when writing asynchronous code, You pass the integer value to the function, not a reference, so the initial variable outside of the function won't be changed, I need to use a future builder to handle this function, and that's Here the File, value) == true, is actually Future<bool> == bool, PREFER starting a non-boolean variable or property comment with a noun phrase, Extension methods are a way to add functionality to , This library provides further tools for creating, consuming and transforming futures and streams, as well as direct access to other asynchronous primitives like Timer, scheduleMicrotask and Zone, I used to believe it was for performance reasons, but then on a 32 bits or 64 bits machine, Oct 22, 2009 · 436 bool exists in the current C - C99, but not in C89/90, e, Oct 5, 2016 · bool is a value type, this means that it cannot be null, so the Nullable type basically allows you to wrap value types, and being able to assign null to them, join(); RegExp implements Dart regular expressions, which provide a grammar for matching patterns within text, PopPageWithRouteMatchCallback = bool Function(Route route, dynamic result, RouteMatchBase match) Signature for a function that takes in a route to be popped with the result and returns a boolean decision on whether the pop is successful, You cannot assign any other values to Booleans, FFI stands for foreign function interface, If watching videos helps you learn, check out this overview of extension methods, Nov 16, 2025 · In this tutorial, we’ve learned overview of a Dart/Flutter Future, how to create a Future simply using delayed or value method, how to work with then-catchError-whenComplete or try-catch-finally with Future async-await, way to handle chain of multiple asynchronous methods or Future wait for multiple futures complete, Sep 15, 2025 · Dart mobile, command-line, and server apps running on the Dart Native platform can use the dart:ffi library to call native C APIs, and to read, write, allocate, and deallocate native memory, Dec 4, 2025 · Properties authenticate ← Future <bool> Function(Uri url, String scheme, String? realm)? Sets the function to be called when a site is requesting authentication, Dart functions are first-class citizens means that you can assign a function to a variable, pass a function to another function as an argument, and return a function from another function, bool / _Bool is a type that can hold either the value true or false, The Boolean data type in DART supports only two values true and false, That way you, your fellow programmers, and your Dec 4, 2025 · Here the File, Oct 22, 2020 · @vietstone A Function can be anything, like Function(), Function(int), etc, which is why with Dart null safety, you should explicitly tell what that Function is, Two common cases are top-level variables and instance variables: Dart often can't determine whether they're set, so it doesn't try, This method returns a view of the mapped elements, Oct 18, 2025 · Constructors are special functions that create instances of classes, Jul 17, 2019 · For now, all types in Dart are nullable, Therefore, you cannot assign the result of the isTextFile() function to the result variable, Sep 24, 2021 · This article explains how to compare two objects in Dart, Aug 30, 2024 · Callbacks are a cornerstone of modern programming, enabling flexible and dynamic function behavior, Change the return type of _onWillPop from Future<bool?> to Future<bool>, dart that's complaining, However, when working with named parameters, you explicitly specify the name of each parameter when calling the Mar 10, 2025 · Records are an anonymous, immutable, aggregate type, now in my main code I want to return a Widget according to the value that got return form that mention function, but I didn't succeed using the returned value right, Future, Stream, and more are in the dart:async library (API reference), This page lists diagnostic messages produced by the Dart analyzer, with details about what those messages mean and how you can fix your code, These types are used to distinguish between Dart values and JS values at compile-time, Oct 16, 2019 · final bool Function(String id, double price) updateItem; bool isPriceUpdated = widget, bool and _Bool, and true and false are language keywords for boolean types, bool is an alias for _Bool if you include stdbool, API docs for the operator == method from the Function class, for the Dart programming language, google, In Flutter development, Dart assertions provide a mechanism to check assumptions about your code's behavior at runtime, Classes cannot extend, implement, or mix in int, A variable of type Boolean stores a reference to a Boolean object, dart:mirrors Returns a function that depending on the provided bool value, invokes and returns the result of either onFalse or onTrue function, Jun 4, 2021 · Prior to null-safe dart, the following was valid syntax: Dec 18, 2021 · During my exploration of Dart, I encountered the following code snippet in the Dart language tour (https://dart, Functions ambiguate <T>(T? value) → T? bodyBytesToString (Stream <List <int>> bodyBytes, Map <String, String> headers) → Future <String> debounce <T>(RxInterface <T> listener, WorkerCallback <T> callback, {Duration? time, Function? onError, void onDone()?, bool? cancelOnError}) → Worker debounce is similar to interval, but sends the last value, Since bool wasn't reserved prior to C99, they use the _Bool keyword (which was reserved), Summary: in this tutorial, you’ll learn how to use the Dart if statement to execute a code block based on a condition, that your code won't use it for its own purposes (similarly for the identifiers true and Dec 14, 2019 · The values for a bool are true and false, whereas for BOOL you can use any int value, though TRUE and FALSE macros are defined in the windef, Default constructors Used to create a new instance when a constructor hasn't been specified, Does it support operator overloading? If yes, can you show me how it's done in a simple example? And what are some advantages etc? Aug 15, 2013 · I would like to pass a primitive (int, bool, ) by reference, When I compare two objects in Dart, it only has == operator which helps me compare two logical memory addresses of two objects in Dart, I don't think we can or perhaps should support mocking classes which change the types of Object's method parameters Notes: VoidCallback is an anonymous function that takes no arguments and returns no value, Dec 31, 2020 · I am a beginner in flutter I try to get the boolean value from the Future< bool> type function And this my Dart language coding file I get following error from 104th line The argument type ' Aug 7, 2025 · Use a noun-phrase for such non-boolean functions, and a phrase starting with "Whether" for such boolean functions, just as for a syntactic property or variable, For example, let's take a look at the program below :, That is, it must be: Total: It must return a boolean for all arguments, Dart 3, Jul 8, 2021 · 4 onWillPop expects a Future<bool> which means return value will either be true or false but the return type of _onBackPressed is Future<bool?> which means the return value be either true, false or null, forEach is expecting a void Function(T) not a bool Function(T), ValueSetter is an anonymous function that takes a value as an argument, which you can use to set some other value, Sep 15, 2025 · Dart libraries are full of functions that return Future or Stream objects, This means that you can't write a statement where Dart expects a value, Although types are mandatory, type annotations are optional because of type inference, With some additional timeout bonus code, Dart implements many types of constructors, Here’s the syntax of the if statement: In this syntax, if the […] Dec 22, 2023 · Dart - The return type 'bool Function ()' isn't a 'bool', as required by the closure's context Asked 1 year, 8 months ago Modified 1 year, 8 months ago Viewed 130 times May 26, 2020 · How do you sort a List in dart based on a bool value, the compareTo method doesn't work with bool, (bool) {} - The default value of an optional parameter must be constant, Generative constructors Creates new instances and initializes instance variables, runes) { var ch = String, Solutions without using default value are: to check if onChange parameter is not null before calling it, or Mar 30, 2020 · 0 You pass a reference of the list to the function, Bool is a well-defined primitive integral type, just like int, char, etc, See also: num the super class for int, Jan 4, 2012 · These data types were added in C99, I want true values to appear at the top of the list, This means that the sizeof operator will yield 1 for bool (the standard states, though, that the size of bool is implementation defined), and 4 for BOOL, Jan 4, 2021 · I read that Dart does not support function overloading, Mar 9, 2021 · Oooh yikes, h header, Mar 8, 2021 · The problem is caused by the return true inside your forEach, It also has mathematical conversions to other integral types, which can sometimes be confusing for people, but I don't think that is the source of your current confusion, Dart has very few ways to do implicit conversion between things of different type, Jan 4, 2022 · A value of type 'bool' can't be returned from the function 'qux' because it has a return type of 'void', The condition in parentheses after if must be an expression that evaluates to a boolean: Dec 4, 2025 · The behavior of the operators and methods in the int class therefore sometimes differs between the Dart VM and Dart code compiled to JavaScript, These functions are asynchronous: they return after setting up a possibly time-consuming operation (such as I/O), without waiting for that operation to complete, Keyword bool is used to define a boolean variable, Jun 16, 2020 · The condition needs to be a boolean, and an integer is-not a boolean, When compiling to Wasm, they execute in separate runtimes as well, Most asynchronous functions are just async Dart functions that depend, possibly deep down, on an inherently asynchronous computation, The default behavior for all Object s is to return true if and only if this object and other are the same object, API docs for the FutureOr class from the dart:async library, for the Dart programming language,