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> you can just start writing in a declarative style and not worry about debugging, because everything is checked by the type system That is dangerously close t

> you can just start writing in a declarative style and not worry about debugging, because everything is checked by the type system That is dangerously close to the infamous "if it compiles, then it works" boast, which Haskellers make all the time (while denying that they make it), demonstrating in the process that they don't write real software, where the defects one encounters are very often of a nature such that the program behaves exactly as intended by its authors, but the intended behavior is itself wrong. How does the type system help here? My comment wasn't glib. I actually think those phenomena quite well explain much Haskell advocacy. Considering how massive an undertaking it is to learn the language and its Byzantinely-complex, PhD-theses-in-disguise libraries (each of which sports a zoo of custom operators) and how small the payoff is, it's unsurprising that those who take the plunge begin zealously encouraging others to do the same, lest their own investment have been for nothing. In a way it's like a conspiracy.

elihu 9y ago
There's no conspiracy; programming in Haskell is the most fun I've ever had with a computer. The "if it compiles, it works" thing describes people's experience. It isn't always true and it isn't a valid excuse not to do proper testing, but in Haskell a non-working solution is usually at least broken in a way that makes sense in the context of the problem you're trying to solve. If you program an incorrect solution to a problem, you'll probably get a wrong answer. But a wrong answer is different than nonsense, which is what you get if, say, you write past the end of an array in C. The Haskell type system is a very good nonsense filter, and probably a majority of programming errors are from telling the program to do something nonsensical. If you filter those out, sometimes what's left is a working program. A Haskell programmer is unlikely to write a several thousand line program and have it work correctly the first time, but even large programs are written in small pieces. When those small pieces work correctly the first time, it's gratifying.
- nv-vn 9y ago
  I'm not sure how this corresponds to your experience with Haskell, but as an OCaml user there's been numerous times where I have been forced to write large chunks of code without a compiler/IDE to aid me at all (e.g. VM wasn't working so had to work from Windows temporarily). In each of these cases, upon compilation, I have been greeted by a flood of errors (syntax errors, type errors, and everything in between). However, without exception, the program has always worked as expected when I ran it the first time. I think it's reasonably plausible that one could write a program the magnitude of ~5k lines in Haskell and have it work on the first attempt.

elihu 9y ago

There's no conspiracy; programming in Haskell is the most fun I've ever had with a computer. The "if it compiles, it works" thing describes people's experience. It isn't always true and it isn't a valid excuse not to do proper testing, but in Haskell a non-working solution is usually at least broken in a way that makes sense in the context of the problem you're trying to solve. If you program an incorrect solution to a problem, you'll probably get a wrong answer. But a wrong answer is different than nonsense, which is what you get if, say, you write past the end of an array in C. The Haskell type system is a very good nonsense filter, and probably a majority of programming errors are from telling the program to do something nonsensical. If you filter those out, sometimes what's left is a working program. A Haskell programmer is unlikely to write a several thousand line program and have it work correctly the first time, but even large programs are written in small pieces. When those small pieces work correctly the first time, it's gratifying.

nv-vn 9y ago
I'm not sure how this corresponds to your experience with Haskell, but as an OCaml user there's been numerous times where I have been forced to write large chunks of code without a compiler/IDE to aid me at all (e.g. VM wasn't working so had to work from Windows temporarily). In each of these cases, upon compilation, I have been greeted by a flood of errors (syntax errors, type errors, and everything in between). However, without exception, the program has always worked as expected when I ran it the first time. I think it's reasonably plausible that one could write a program the magnitude of ~5k lines in Haskell and have it work on the first attempt.