PureScript

He started to work on PureScript since he wasn't satisfied by other attempts to transpile Haskell to JavaScript (e.g. using Fay, Haste, or GHCJS).

Additional core tools developed by the community include the dedicated build tool "Pulp",[10] the documentation directory "Pursuit",[11] and the package manager "Spago"[12] PureScript features strict evaluation, persistent data structures and type inference.

PureScript's type system adds support for row polymorphism and extensible records.

[13] However, PureScript lacks support for some of the more advanced features of Haskell like GADTs and type families.

PureScript supports type-driven development via its typed holes feature,[19] in which a program can be constructed with missing subexpressions.