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I think dynamically types languages are on their way out. There aren't many good arguments remaining in favor of them.

by fierro 8y ago

ken 8y ago
I don’t think that’s the problem. I wouldn’t use Python (especially 2.x), but I’d have no hesitation with using Common Lisp. It has lots of great features for programming in-the-large that Python simply lacks.
- yuchi 8y ago
  Genuinely asking: could you provide some specific example? What does CL has that Pythos doesn’t? (Disclaimer: i never worked on neither)
  - chalst 8y ago
    If I had to point to something, I would single out CL's powerful support for multiple dispatch. I'd hesitate to recommend CL to undisciplined programmers, because it is too easy to write code that works but you don't understand a week later.
    - ken 8y ago
      Multiple dispatch is a big one. Also, macros, which are what (the view layer of) CLOS is built with. In most other object oriented languages, the language isn’t powerful enough to implement its own object system. Having the full power of function calls in all cases (named or anonymous) is incredibly helpful. I know the Python party line is “just use def” but adding a line here and a line there adds up fast. A syntax for function objects is also great. I’ll also call out the ability to use dynamic or lexical scoping on a per-variable basis. That has saved me hundreds of lines of work, and made an O(1) change actually an O(1) patch.
    - ken 8y ago
      (I hammered out that answer right before I had to run on stage. A couple other big items I forgot:) A proper numeric tower. Python has complex numbers, but they don't seem well integrated (why is math.cos(1+2j) a TypeError?). Fractions are frequently very useful, too, and Python has them, in a library, but "import fractions; fractions.Fraction(1,2)" is so much more verbose than "1/2" that nobody seems to ever use them. Conditions! Lisp's debugger capabilities are amazing. And JWZ was right: sometimes you want to signal without throwing. Once you've used conditions, you'll have trouble going back to exceptions. They feel restrictive. (I've come to accept that in a language with immutable data types, like Clojure, exceptions make sense. Exceptions feel out of place, though, in a language with mutability.) Other big wins: keywords, multiple return values, FORMAT (printf on steroids), compile-time evaluation, a native compiler (and disassembler) with optional type declarations. Lisp is unique among the languages I've used in that it has lots of features that seem designed to make writing large programs easier, and the features are all (for the most part) incredibly cohesive.
      - chalst 8y ago
        Conditions, yes. If you have multiple dispatch, then building/supporting a numeric tower is natural. In your other reply you pointed out macros. They are a mixed blessing, easily misused. Other languages have them but use them more sparingly and making it harder to overlook their special status, which leads to better "code smell" in my opinion. Do take a look at Julia. It has learned deeply from CL and innovated further.
        ken 8y ago
        I can imagine how multiple dispatch could make a numeric tower a little easier to implement, but the limitations I see in Python and other languages don't appear to stem from that. You can already take the math.cos of most types of numbers (int, float, even fractions.Fraction, ...) just fine, or add a complex and a Fraction. Python has long dealt with two types of strings, several types of numbers, etc., with the same interfaces. This isn't a difficult problem to solve with single dispatch. Macros are easily misused, true, but so can any language feature. I can go on r/programminghorror and see misuses of if-statements. It's the classic argument against macros, and I hear it a lot, but I can't say I've seen it happen. 25 years ago, conventional wisdom said that closures were too complex for the average programmer, and today they're a necessary part of virtually every language. Could we be reaching the point where syntactic abstraction is simply a concept that every programmer needs to be able to understand? I think "macros are easy to misuse" comes from viewing macros as an island. In some languages (like C), they are: they don't really integrate with any other part of the language. In Lisp, they're a relatively small feature that builds on the overall design of the language. Omitting macros would be like a periodic table with one box missing. It'd mean we get language expressions as native data types, and can manipulate them, and control the time of evaluation, but we just can't manipulate them at compile time.
chalst 8y ago
I have a very high opinion of Julia's dynamic type system. Some static type systems are not very expressive, e.g., Elm, which encourages hacky workarounds. Julia's type system encourages specificity, which exposes problems early.
- SolarNet 8y ago
  That's because it's a strong type system (as opposed to python's weak one where objects can change their shape anytime). Even calling it dynamic is a sort of lie since the compiler is always able to reason about the types it is given due to the way Julia's JIT compiler works. It's "dynamic" in the same way passing around `void*` (or `object`) is "static". That being said Julia's type system is definitely the way of the future in my opinion.
  - jcbrand 8y ago
    Python is strongly typed. See here: https://wiki.python.org/moin/Why%20is%20Python%20a%20dynamic%20language%20and%20also%20a%20strongly%20typed%20language https://wiki.python.org/moin/Why%20is%20Python%20a%20dynamic... "objects can change their shape anytime" is a function of dynamic typing and is orthogonal to strong or weak typing.
    - SolarNet 8y ago
      In a dynamic language "strong" vs "weak" typing really depends on the standard library. All the examples in the given link - for example - focus on the addition function in the standard library. So here are some counter examples: Everything can be used as a bool. This was often used to check for None, but had some issues when used with - for example - datetimes which evaluated midnight as false. In part due to the fact the integer 0 evaluates to false. Changing type unexpectedly is the key example given in your link (`"foo" + 3` is `"foo3"`). Meanwhile in python `foo.method()` can change the type of the variable foo. Which is a level of fuckery commonly found in javascript. Let alone the fact that dynamic duck typing encourages weak typing over performing explicit conversions. This is embodied by "easier to ask forgiveness than permission" which says it's better to catch the type conversion exception than check if the type is an integer ahead of time. Which then leads to implementing javascript-esque add functions anyway. I'll grant you python is stronger than some other dynamic languages, but it is still at least half an order of magnitude weaker than Julia, which is strong in ways approaching Haskell.
spricket 8y ago
I agree, because type inference in some (Typescript) is good enough that there's almost no overhead. Back when it took twice as many lines with types it made sense. But the overhead in typescript is maybe 10%, worth it anymore? I don't think so
- chuckdries 8y ago
  I think we have a ways to go. Typescript's type system is very feature complete (which is a good thing, but it also means there's a lot to learn, and I feel like I have to think about type definitions more than I ever did with other languages), but also, fantastic libraries like Ramda have a lot of trouble with expressing their types with Typescript. It's a tough problem to solve, and I still use both, but I'm just saying we're not there yet.
  - spricket 8y ago
    I agree that the type system is very complex. I've spent a lot of time wrapping my head around it and still get confused sometimes. Unfortunately Typescript's type system is largely driven by the need to represent anything you can do in JS, for library compatibility reasons. The main designer also wrote C# and Delphi. In a lot of ways, C#'s type system is better (less complex), but Typescript has the huge advantage of working with existing JS
jononor 8y ago
I think the dynamic/static typing dichotomy is on its way out (finally!). In dynamic languages optional/gradual typing is getting adopted (ex: Typescript/Flow for JS, Mypy for Python). In static languages type inference is getting standard (ex: Rust/Scala/Kotlin, auto in C++11).

I think dynamically types languages are on their way out. There aren't many good arguments remaining in favor of them.

by fierro 8y ago

I think dynamically types languages are on their way out. There aren't many good arguments remaining in favor of them.

ken 8y ago

I don’t think that’s the problem. I wouldn’t use Python (especially 2.x), but I’d have no hesitation with using Common Lisp. It has lots of great features for programming in-the-large that Python simply lacks.

yuchi 8y ago
Genuinely asking: could you provide some specific example? What does CL has that Pythos doesn’t? (Disclaimer: i never worked on neither)
- chalst 8y ago
  If I had to point to something, I would single out CL's powerful support for multiple dispatch. I'd hesitate to recommend CL to undisciplined programmers, because it is too easy to write code that works but you don't understand a week later.
  - ken 8y ago
    Multiple dispatch is a big one. Also, macros, which are what (the view layer of) CLOS is built with. In most other object oriented languages, the language isn’t powerful enough to implement its own object system. Having the full power of function calls in all cases (named or anonymous) is incredibly helpful. I know the Python party line is “just use def” but adding a line here and a line there adds up fast. A syntax for function objects is also great. I’ll also call out the ability to use dynamic or lexical scoping on a per-variable basis. That has saved me hundreds of lines of work, and made an O(1) change actually an O(1) patch.
  - ken 8y ago
    (I hammered out that answer right before I had to run on stage. A couple other big items I forgot:) A proper numeric tower. Python has complex numbers, but they don't seem well integrated (why is math.cos(1+2j) a TypeError?). Fractions are frequently very useful, too, and Python has them, in a library, but "import fractions; fractions.Fraction(1,2)" is so much more verbose than "1/2" that nobody seems to ever use them. Conditions! Lisp's debugger capabilities are amazing. And JWZ was right: sometimes you want to signal without throwing. Once you've used conditions, you'll have trouble going back to exceptions. They feel restrictive. (I've come to accept that in a language with immutable data types, like Clojure, exceptions make sense. Exceptions feel out of place, though, in a language with mutability.) Other big wins: keywords, multiple return values, FORMAT (printf on steroids), compile-time evaluation, a native compiler (and disassembler) with optional type declarations. Lisp is unique among the languages I've used in that it has lots of features that seem designed to make writing large programs easier, and the features are all (for the most part) incredibly cohesive.
    - chalst 8y ago
      Conditions, yes. If you have multiple dispatch, then building/supporting a numeric tower is natural. In your other reply you pointed out macros. They are a mixed blessing, easily misused. Other languages have them but use them more sparingly and making it harder to overlook their special status, which leads to better "code smell" in my opinion. Do take a look at Julia. It has learned deeply from CL and innovated further.
      - ken 8y ago
        I can imagine how multiple dispatch could make a numeric tower a little easier to implement, but the limitations I see in Python and other languages don't appear to stem from that. You can already take the math.cos of most types of numbers (int, float, even fractions.Fraction, ...) just fine, or add a complex and a Fraction. Python has long dealt with two types of strings, several types of numbers, etc., with the same interfaces. This isn't a difficult problem to solve with single dispatch. Macros are easily misused, true, but so can any language feature. I can go on r/programminghorror and see misuses of if-statements. It's the classic argument against macros, and I hear it a lot, but I can't say I've seen it happen. 25 years ago, conventional wisdom said that closures were too complex for the average programmer, and today they're a necessary part of virtually every language. Could we be reaching the point where syntactic abstraction is simply a concept that every programmer needs to be able to understand? I think "macros are easy to misuse" comes from viewing macros as an island. In some languages (like C), they are: they don't really integrate with any other part of the language. In Lisp, they're a relatively small feature that builds on the overall design of the language. Omitting macros would be like a periodic table with one box missing. It'd mean we get language expressions as native data types, and can manipulate them, and control the time of evaluation, but we just can't manipulate them at compile time.

chalst 8y ago

I have a very high opinion of Julia's dynamic type system. Some static type systems are not very expressive, e.g., Elm, which encourages hacky workarounds. Julia's type system encourages specificity, which exposes problems early.

SolarNet 8y ago
That's because it's a strong type system (as opposed to python's weak one where objects can change their shape anytime). Even calling it dynamic is a sort of lie since the compiler is always able to reason about the types it is given due to the way Julia's JIT compiler works. It's "dynamic" in the same way passing around `void*` (or `object`) is "static". That being said Julia's type system is definitely the way of the future in my opinion.
- jcbrand 8y ago
  Python is strongly typed. See here: https://wiki.python.org/moin/Why%20is%20Python%20a%20dynamic%20language%20and%20also%20a%20strongly%20typed%20language https://wiki.python.org/moin/Why%20is%20Python%20a%20dynamic... "objects can change their shape anytime" is a function of dynamic typing and is orthogonal to strong or weak typing.
  - SolarNet 8y ago
    In a dynamic language "strong" vs "weak" typing really depends on the standard library. All the examples in the given link - for example - focus on the addition function in the standard library. So here are some counter examples: Everything can be used as a bool. This was often used to check for None, but had some issues when used with - for example - datetimes which evaluated midnight as false. In part due to the fact the integer 0 evaluates to false. Changing type unexpectedly is the key example given in your link (`"foo" + 3` is `"foo3"`). Meanwhile in python `foo.method()` can change the type of the variable foo. Which is a level of fuckery commonly found in javascript. Let alone the fact that dynamic duck typing encourages weak typing over performing explicit conversions. This is embodied by "easier to ask forgiveness than permission" which says it's better to catch the type conversion exception than check if the type is an integer ahead of time. Which then leads to implementing javascript-esque add functions anyway. I'll grant you python is stronger than some other dynamic languages, but it is still at least half an order of magnitude weaker than Julia, which is strong in ways approaching Haskell.

spricket 8y ago

I agree, because type inference in some (Typescript) is good enough that there's almost no overhead. Back when it took twice as many lines with types it made sense. But the overhead in typescript is maybe 10%, worth it anymore? I don't think so

chuckdries 8y ago
I think we have a ways to go. Typescript's type system is very feature complete (which is a good thing, but it also means there's a lot to learn, and I feel like I have to think about type definitions more than I ever did with other languages), but also, fantastic libraries like Ramda have a lot of trouble with expressing their types with Typescript. It's a tough problem to solve, and I still use both, but I'm just saying we're not there yet.
- spricket 8y ago
  I agree that the type system is very complex. I've spent a lot of time wrapping my head around it and still get confused sometimes. Unfortunately Typescript's type system is largely driven by the need to represent anything you can do in JS, for library compatibility reasons. The main designer also wrote C# and Delphi. In a lot of ways, C#'s type system is better (less complex), but Typescript has the huge advantage of working with existing JS

jononor 8y ago

I think the dynamic/static typing dichotomy is on its way out (finally!). In dynamic languages optional/gradual typing is getting adopted (ex: Typescript/Flow for JS, Mypy for Python). In static languages type inference is getting standard (ex: Rust/Scala/Kotlin, auto in C++11).