Ranked in these QuestionsQuestion Ranking
Pro Has Typeclasses and RankNTypes
Pro Type safety
Compiling should be your first unit test. A tight type system (static and hopefully strong) will catch many logic errors that are often difficult to spot through debugging. In languages like PureScript, if it compiles, it often runs properly.
Pro Modules can be compiled to CommonJS
Pro High performance FFI code
Pro Has row polymorphism and extensible effects
Pro Awesome web frameworks
Halogen (VDOM, similar to ELM)
And hit these up with Signals, Isolated/(Managed?) Components, powerful functions and FFI
Pro Small output
Fay produces smaller output than pure Haskell compilers such as GHCJS; It does not need to include the whole Haskell runtime, as it drops support for features such as multi-threading, giving it fewer dependencies.
Pro Simple, flexible, hackable FFI
max = ffi "Math.round(%1,%2)"
concat, though they must expose an explicit number of parameters to Fay.
Pro Easy to set up, with packages available on Cabal
Fay is available on Cabal, as are Fay packages, so getting up and running is as simple as typing 'cabal install'. Happstack, Snap, and Yesod packages are available on Hackage, as are bindings for JQuery and Backbone.
Pro Subset of Haskell - nothing new to learn
Since Fay is a subset of Haskell - Lazy, statically typed, and pure by default. There's no new syntax to learn, and no surprises when it comes to the semantics of your code. This extends into function names as well - Fay programmers can use familiar functions such as
Con Lots of dependencies needed to get started
Purescript is written in Haskell, but meant to be used with Node.js. As a result, to get started , users must install ghc, cabal, node.js, grunt, and bower. Purescript also has its own compiler, and different semantics form Haskell, and so even after installing, there's still some overhead to getting productive with Purescript.
Con Restrictive FFI
Con Lack of good IDE/tooling support.
Con Slow compilation
On large project, for example Halogen
Con No typeclasses
This can cause some overhead.