When comparing Flow vs Haste, the Slant community recommends Haste for most people. In the question“What are the best solutions to "The JavaScript Problem"?” Haste is ranked 3rd while Flow is ranked 32nd. The most important reason people chose Haste is:
Haste was designed to allow both the client and server to be written as parts of the same, type-safe application. This is in stark contrast to most other options, where the client and server are considered two separate entities, resulting in extra manual validation code and more chances for type errors.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Checks to see if you check for Nulls
Because getting those exceptions is just not fun and very pervasive.
Pro Versioned type definitions
Pro There is support in many code editors via the extension
For example, there is good support through the extension in Visual Studio Code, which is a good editor for TypeScript, which is a competitor to Flow.
Pro Babel extension for strip of type annotations
Thanks to the Babel extension for the output, there is minimally modified code that is understandable to the author.
Pro Statical analysing of JavaScript code
Statical analysing of JavaScript code without pre-making any changes to it. But supported annotation types by extending the syntax of the language.
Pro Client and Server as the same application
Haste was designed to allow both the client and server to be written as parts of the same, type-safe application. This is in stark contrast to most other options, where the client and server are considered two separate entities, resulting in extra manual validation code and more chances for type errors.
Pro Almost full power of Haskell
Haste supports the Haskell 2010 standard except for Template Haskell as well as most GHC extensions.
Pro Automatic, type safe program slicing
Haste lets you write client and server as a single program, automatically generating code for the server as well as the client, giving you full type safety even across the Internet.
Pro Generates small, reasonably performant code
Cons
Con Weak base type definitions even for popular JavaScript libraries
For example, there are definitions for Gulp, React.
Con Lacks some minor Haskell functionality
Lacks support for Template Haskell.