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I have been programming for 20 years, and yet despite having used dynamic languages I don’t actually know what it means to leverage dynamic programming techniqu

I have been programming for 20 years, and yet despite having used dynamic languages I don’t actually know what it means to leverage dynamic programming techniques. For instance, I’ve never encountered a JavaScript codebase that I have thought couldn’t benefit from just being statically typed with Typescript. I get the impression that dynamic programming, besides the odd untyped line of code, is best used only for extremely specific cases?

hbrn 3y ago
> For instance, I’ve never encountered a JavaScript codebase that I have thought couldn’t benefit from just being statically typed with Typescript That's the type bias. If you look at a non-typed codebase, it always feels like it will be better with types. But if you had a chance to go back in time and start the same codebase in Typescript, it would actually come out way worse than what you have today. Types can be great when used sparingly, but with Typescript everyone seems to fall into a trap of constantly creating and then solving "type puzzles" instead of building what matters. If you're doing Typescript, your chances of becoming a product engineer are slim.
cjbgkagh 3y ago
To be clear I wasn't referring 'dynamic programming' but as you say, the use of a dynamic language, or programming without types, mimicking what I assumed the original poster I replied to meant. My guess is that interviewees wishing to return to the typed world they are comfortable with would first try to type the JSON they are working with. Given that the JSON is messy this could be an unbounded amount of work that is unlikely to pay-off within the span of an interview.
- IshKebab 3y ago
  Ok that is very confusing because "dynamic programming" is a very specific thing, and also super popular in leetcode questions. Maybe half the questions on leetcode.com involve dynamic programming. It has absolutely nothing to do with dynamically typed programming. It's also a really terrible name for what is essentially caching.
- sakex 3y ago
  I'm curious about what context would require an untyped language
  - cjbgkagh 3y ago
    By untyped I assume you mean dynamic languages? I’m some contexts it’s not convenient to lug around a type checker, embedded languages for example. Other times if doing macro heavy programming (lisp, forth) it’s hard to build a type system that can properly type check the code or resolve the implicit types in a reasonable amount of time. In the context of JSON you can work on it without types from a typed language. It’s just that as a force of habit coders may chose to spend time adding types to things when they shouldn’t.
waffletower 3y ago
There is much naïveté among the strongly typed herd. When tasked to create glue code translating between two opposing type systems, which is a very common data engineering task, reaching for a strongly typed language is never the best option for code complexity and speed of development. Yet the hammer will often succeed if you hit hard enough and club the nail back to shape when you invariably bend it.
- throwaway2037 3y ago
  There is much naïveté among the strongly typed herd. Is exactly the reverse also true? Let me try: "There is much naïveté among the weakly typed herd." For every person who thinks Python or Ruby can be used for everything, there is another person who thinks the same for C++ or Rust. Also, the example that you gave is incredibly specific: When tasked to create glue code translating between two opposing type systems, which is a very common data engineering task Can you provide a concrete example? And what is "data engineering"? I never heard that term before this post.
  - Hasnep 3y ago
    I'm a data engineer, it's a fairly new role so it's not well defined yet, but most data engineers write data pipelines to ingest data into a data warehouse and then transform it for the business to use. I'm not sure why using a static language would make translating data types difficult, but I add as many typehints as possible to my Python so I rarely do anything with dynamic types. I guess they're saying for small tasks where you're working with lots of types, when using a static language most of your code will be type definitions, so a dynamic language will let you focus on writing the transformation code.
    - waffletower 3y ago
      Using a static language to manipulate complex types, particularly those sourced from a different type system (say complex nested Avro, SQL, or even complex JSON) is much more awkward when the types cannot be normalized into the language automatically as can be done with dynamic languages. Static languages require more a priori knowledge of data types, and are very awkward at handling collections with diverse type membership. Data has many forms in reality -- dynamic languages are much more effective at manipulating data on its own terms.
lolinder 3y ago
The problem is the word dynamic is overloaded, and I'm not at all sure which one your parent comment meant. "Dynamic programming" traditionally has nothing to do with dynamic languages but is instead a class of algorithms that are "dynamic" in the sense that they represent time.[0] This might be what your parent was referring to because these algorithms lend themselves well to Haskell's lazy evaluation, and they reference F# as being eager. That said, they also talk about F# as being type safe, so they could also be referring to dynamic programming languages. The grandparent was definitely referring to this one, but "dynamic programming techniques" sounds much more like the algorithmic meaning. [0] https://en.m.wikipedia.org/wiki/Dynamic_programming https://en.m.wikipedia.org/wiki/Dynamic_programming

hbrn 3y ago

> For instance, I’ve never encountered a JavaScript codebase that I have thought couldn’t benefit from just being statically typed with Typescript That's the type bias. If you look at a non-typed codebase, it always feels like it will be better with types. But if you had a chance to go back in time and start the same codebase in Typescript, it would actually come out way worse than what you have today. Types can be great when used sparingly, but with Typescript everyone seems to fall into a trap of constantly creating and then solving "type puzzles" instead of building what matters. If you're doing Typescript, your chances of becoming a product engineer are slim.

cjbgkagh 3y ago

To be clear I wasn't referring 'dynamic programming' but as you say, the use of a dynamic language, or programming without types, mimicking what I assumed the original poster I replied to meant. My guess is that interviewees wishing to return to the typed world they are comfortable with would first try to type the JSON they are working with. Given that the JSON is messy this could be an unbounded amount of work that is unlikely to pay-off within the span of an interview.

IshKebab 3y ago
Ok that is very confusing because "dynamic programming" is a very specific thing, and also super popular in leetcode questions. Maybe half the questions on leetcode.com involve dynamic programming. It has absolutely nothing to do with dynamically typed programming. It's also a really terrible name for what is essentially caching.
sakex 3y ago
I'm curious about what context would require an untyped language
- cjbgkagh 3y ago
  By untyped I assume you mean dynamic languages? I’m some contexts it’s not convenient to lug around a type checker, embedded languages for example. Other times if doing macro heavy programming (lisp, forth) it’s hard to build a type system that can properly type check the code or resolve the implicit types in a reasonable amount of time. In the context of JSON you can work on it without types from a typed language. It’s just that as a force of habit coders may chose to spend time adding types to things when they shouldn’t.

waffletower 3y ago

There is much naïveté among the strongly typed herd. When tasked to create glue code translating between two opposing type systems, which is a very common data engineering task, reaching for a strongly typed language is never the best option for code complexity and speed of development. Yet the hammer will often succeed if you hit hard enough and club the nail back to shape when you invariably bend it.

throwaway2037 3y ago
There is much naïveté among the strongly typed herd. Is exactly the reverse also true? Let me try: "There is much naïveté among the weakly typed herd." For every person who thinks Python or Ruby can be used for everything, there is another person who thinks the same for C++ or Rust. Also, the example that you gave is incredibly specific: When tasked to create glue code translating between two opposing type systems, which is a very common data engineering task Can you provide a concrete example? And what is "data engineering"? I never heard that term before this post.
- Hasnep 3y ago
  I'm a data engineer, it's a fairly new role so it's not well defined yet, but most data engineers write data pipelines to ingest data into a data warehouse and then transform it for the business to use. I'm not sure why using a static language would make translating data types difficult, but I add as many typehints as possible to my Python so I rarely do anything with dynamic types. I guess they're saying for small tasks where you're working with lots of types, when using a static language most of your code will be type definitions, so a dynamic language will let you focus on writing the transformation code.
  - waffletower 3y ago
    Using a static language to manipulate complex types, particularly those sourced from a different type system (say complex nested Avro, SQL, or even complex JSON) is much more awkward when the types cannot be normalized into the language automatically as can be done with dynamic languages. Static languages require more a priori knowledge of data types, and are very awkward at handling collections with diverse type membership. Data has many forms in reality -- dynamic languages are much more effective at manipulating data on its own terms.

lolinder 3y ago

The problem is the word dynamic is overloaded, and I'm not at all sure which one your parent comment meant. "Dynamic programming" traditionally has nothing to do with dynamic languages but is instead a class of algorithms that are "dynamic" in the sense that they represent time.[0] This might be what your parent was referring to because these algorithms lend themselves well to Haskell's lazy evaluation, and they reference F# as being eager. That said, they also talk about F# as being type safe, so they could also be referring to dynamic programming languages. The grandparent was definitely referring to this one, but "dynamic programming techniques" sounds much more like the algorithmic meaning. [0] https://en.m.wikipedia.org/wiki/Dynamic_programming https://en.m.wikipedia.org/wiki/Dynamic_programming