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Most Haskellers write out the types even though they can be inferred. In a pure language, signatures are extremely close to documentation (you know exactly what
by ilovecaching 8y ago
Most Haskellers write out the types even though they can be inferred. In a pure language, signatures are extremely close to documentation (you know exactly what a function will do by its signature).
Java requires more code than Python or Haskell because it's extremely imperative and statement based. Python on the other hand includes a lot of functional, more expressive idioms like concise list comprehensions.
- omaranto 8y ago> Most Haskellers write out the types even though they can be inferred. I don't think that's true. Idiomatic Haskell has explicit declarations only for top level functions and uses type inference for everything else.
- jose_zap 8y agoI often copy paste the inferred type to top level declarations, so I’m a sense it is true
- FranzFerdiNaN 8y agoTypes aren’t documentation, no matter how many Haskell users delude themselves thinking it is. Documentation is more than a function definition. Types don’t explain rationales and how to use functions and programs. Types don’t give proper examples.
- hasahmed 8y agoIt's better documentation than no documentation
- chowells 8y agoTypes are really good documentation. I can tell I'm not deluded by thinking so because I can sit down with a Haskell library containing zero examples and write code that uses it. If your assertion was correct, that would be impossible. But it's not only possible, it's easy. Perhaps there is more to types than you realize.
- pmoriarty 8y agoAlice: Hey Bob, want to try my nifty new function? Bob: Sure, Alice, what does it do? Alice: It takes an object and it returns an object. Bob: But what does it actually do? Alice: I told you. It takes an object and it returns an object. Bob: But what does it do with the object? What's it for? Why should I use it? Alice: Hey, I just gave you the full documentation for my function. You have everything you need. Now go use it. Bob: Um, no thanks. I like to know more about what I'm getting myself in to.
- xboxnolifes 8y agoThankfully, Haskell supports much nicer types than only `Object`
- pvorb 8y agoAlice: Hey Bob, want to try my nifty new function? Bob: Sure, Alice, what does it do? Alice: It takes a string and it returns an integer. Bob: But what does it actually do? Alice: I told you. It takes a string and it returns an integer. Bob: But what does it do with the string? What's it for? Why should I use it? Alice: Hey, I just gave you the full documentation for my function. You have everything you need. Now go use it. Bob: Um, no thanks. I like to know more about what I'm getting myself in to.
- ilovecaching 8y agoI think you're criticizing a language you have no experience in. Haskell development is type driven. You start by defining and constraining your types until you get a DSL to write signatures in. See the Idris O'reilly book for more on type driven development. By the time you've added type constrains through typeclasses, selected types named after the domain, and selected a suitable name for the function, it's possible to write against the signature with no knowledge of the body or comments. You're also forgetting that signature includes the name of the function. reverse :: [a] -> [a] is easy to understand by it's name and type.
- StavrosK 8y agoTypes are documentation. Documentation isn't types.
- ilovecaching 8y agoI suggest reading Type-Driven Development with Idris by Edwin Brady. I don't think you have enough experience writing Haskell to understand the outcome of type driven development. In Haskell you start by defining your domain as types, and constrain those types with typeclasses. By the time you get to writing signatures, the implementations can almost be inferred (in Idris they actually can be inferred, the code literally writes itself). In an imperative language with side effects, examples and documentation are a must because behavior is hidden in the body of a function; the signatures lie. A journeyman Haskeller can write code that is completely self documenting. No examples are required, because the types coupled with the purity of the language allows us to tell the whole story.
- Buttons840 8y agoThis is (probably often) true for all those who can load a few dozen arbitrary type signatures into their active memory and start drawing conclusions. For the rest of us a few examples of how to do common things would help a lot. Please include documentation. I have experienced what you're talking about with Haskell but it was a lot of uncomfortable work. But it's "technically" true that the types often describe how to use a library, sometimes so well that errors cannot happen.
- pytester 8y ago>In a pure language, signatures are extremely close to documentation (you know exactly what a function will do by its signature). The same can be true of tests. I've started generating API documentation from mine: e.g. https://hitchdev.com/strictyaml/using/alpha/scalar/email-and-url/ https://hitchdev.com/strictyaml/using/alpha/scalar/email-and... I tend to think of types and tests as attacking the same problem from opposite directions.
- sethammons 8y ago> StrictYAML can validate emails (using a simplified regex) Public Service Announcement: don't validate emails with regex. Every time you do, god kills a kitten.
- pytester 8y agoJust checking for the @ symbol is fair game. Anything beyond that is a bad idea.
- sethammons 8y agoAgreed :)
- YouAreGreat 8y ago> Most Haskellers write out the types Maybe that's partly because Haskell can easily become a bit too elegant. Between all the currying and combinators, the type helps to understand code "top down", i.e. when you don't have studied and memorized all "bottom up" component parts.