| Features |
| didn't | never | nice | essential |
| answer | use | to have | to me |
| Arrow notation | 37% | 29% | 26% | 8% |
| Assertions | 44% | 18% | 30% | 9% |
| Built-in support for classes Typeable and Data | 47% | 17% | 24% | 12% |
| Concurrent Haskell (MVars etc) | 33% | 21% | 24% | 21% |
| Data types with no constructors | 44% | 20% | 26% | 11% |
| Derivable type classes | 47% | 19% | 21% | 14% |
| Existential data constructors | 46% | 12% | 22% | 21% |
| Explicitly-kinded quantification | 47% | 24% | 21% | 8% |
| For-alls to right of arrow | 49% | 21% | 22% | 9% |
| Foreign language interface | 25% | 11% | 21% | 43% |
| Functional dependencies | 45% | 11% | 18% | 26% |
| Generalised algebraic data types | 44% | 16% | 29% | 11% |
| Generalised derived instances for newtypes | 48% | 14% | 30% | 9% |
| Generating or compiling External Core | 40% | 39% | 16% | 5% |
| Higher-rank polymorphism | 43% | 11% | 21% | 25% |
| Implicit parameters | 48% | 32% | 16% | 4% |
| Infix type constructors | 38% | 18% | 33% | 12% |
| Lexically scoped type variables | 46% | 18% | 24% | 12% |
| Liberalised type synonyms | 49% | 18% | 25% | 8% |
| Linear implicit parameters | 52% | 37% | 9% | 2% |
| Overlapping instances | 45% | 16% | 23% | 15% |
| Packages | 29% | 8% | 31% | 33% |
| Parallel List Comprehensions | 40% | 28% | 26% | 7% |
| Pattern guards | 35% | 17% | 32% | 17% |
| Rebindable syntax | 43% | 36% | 18% | 3% |
| Recursive modules | 37% | 28% | 27% | 9% |
| Rewrite rules | 48% | 29% | 20% | 4% |
| Space profiling | 29% | 15% | 31% | 25% |
| Template Haskell | 32% | 28% | 31% | 9% |
| The recursive do-notation | 39% | 29% | 22% | 10% |
| Time profiling | 28% | 14% | 30% | 28% |
| Unboxed types and primitive operations | 43% | 14% | 28% | 15% |
| Undecidable instances | 48% | 21% | 20% | 11% |
| ghc --make (built-in make) | 26% | 7% | 32% | 35% |
| ghc -M (dependency generation) | 34% | 26% | 26% | 13% |
| ghc -O (code optimisation capabilities) | 26% | 6% | 26% | 42% |
| ghc -e (expression evaluation) | 35% | 39% | 21% | 5% |
| ghci (interactive version) | 17% | 3% | 19% | 61% |