5 ms·

XSL/T just kept getting better; like, I agree with exactly what you said for 1.0--which sadly is all libxslt (and thereby browsers that relied on it) ever suppo

by saurik 6y ago

XSL/T just kept getting better; like, I agree with exactly what you said for 1.0--which sadly is all libxslt (and thereby browsers that relied on it) ever supported--but XSL/T 2.0 was pretty epic, and there is now even a 3.0 as of a few years ago.

emmanueloga_ 6y ago
Agreed, XSLT 3.0 is amazing... and XQuery provides a more palatable syntax, with similar semantics. Kinda ironic that given the problem definition no solution has been provided on XQuery or XSLT yet, the widely used domain specific languages that better suit the problem :-). I believe there's a lot of inspiration to be had from the X-family of languages. The "secret sauce" is XPath. We need a new language drawing inspiration from the tree processing of X* languages but with more modern syntax and less with a less byzantine type system (read: anything but XML Schema :-). Less angle brackets would help too! --- Bonus points: add tuples and prolog like queries to such language (thinking of SPARQL) ... now that would be something really powerful.
- bmn__ 6y ago
  > We need a new language drawing inspiration This exists (optics/lenses), but most programmers don't know about it. I expect this to hit mainstream programming languages a few years later. I don't know of a simple, jargon-free explanation of the concepts. WP is useless, sadly. http://enwp.org/Bidirectional_transformation http://enwp.org/Bidirectional_transformation Also see: https://news.ycombinator.com/item?id=24710565 https://news.ycombinator.com/item?id=24710565
  - josevalim 6y ago
    Thanks for sharing! Solutions to this problem in the vein of jq and optics were precisely why I started the repo above.
  - bradrn 6y ago
    > This exists (optics/lenses), but most programmers don't know about it. … I don't know of a simple, jargon-free explanation of the concepts. Let me have a go! I’d explain optics/lenses as giving field access as a data structure. That is, a lens is an object which describes how to access an element from a ‘larger’ value. For example, you can define _1 and _2 as lenses for accessing the first and second element respectively of a tuple: _1 :: Lens' (a,b) a _2 :: Lens' (a,b) b (Using Haskell syntax here as that’s what I know best, though I’ve simplified the types slightly.) The great advantage of having these as first-class values is that you can now manipulate them. Of course, the main things you’ll want to do with these are get and set things: > (1,2) ^. _1 1 > (1,2) & _1 .~ 3 (3,2) More interestingly, you can also use a function to modify the value to which a lens is pointing: > (1,2) & _1 %~ negate (-1,2) Most usefully, you can also compose lenses. For instance, to get the second element of the first element of a nested tuple, you can compose _2 and _1 using dot notation: _1._2 :: Lens' ((a,b),c) b Or, for a more realistic example, here’s a lens which accesses the ‘numSeen’ field of the value corresponding to key "keyToIncrement": (ix "keyToIncrement")._numSeen :: Lens' (Map String MyStructure) Int (Well, strictly speaking, this is actually a traversal or a prism or something, because "keyToIncrement" might not exist, but let’s ignore that for this really simple example…) And now that you have it, you can use this new lens to do anything you want with this value: you can get it, set it, increment it, decrement it, print it, etc. Additionally, you don’t have to restrict yourself to just lenses. For example, ‘traversals’ are a generalisation of lenses which allow you to access 0, 1 or more elements, rather than restricting access to just one element at a time. For instance, you can use ‘both’ to transform, well, both elements of a tuple: > (1,2) & both 5~ negate (-1,-2) Or you can use ‘traversed’ to access each element of, say, a list: > [1,2,3,4,5] & traversed .~ 0 [0,0,0,0,0] Of course, there are other ways of doing each of these. If you happen to be working with mutable values, you can sometimes use dot notation to access deeply nested fields. Some usecases of ‘traversed’ can be replaced by a map. However, there really is no comparable substitute for lenses when working with deeply nested immutable structures, especially ones of unknown shape.
    - alehander42 6y ago
      thanks! i think i now understood the idea
  - emmanueloga_ 6y ago
    optics/lenses solve this problem in a framework that is jargon-heavy and difficult to understand, and most implementations I've seen use languages with very strict type system. The XSLT+XPath approach is more dynamic, easier to grasp (imho) and can probably be learned in an afternoon. Tradeoffs, tradeoffs... I wouldn't want to write most programs in Haskell but you could write pretty much any program in, say, JavaScript ... :-)

by saurik 6y ago

emmanueloga_ 6y ago

Agreed, XSLT 3.0 is amazing... and XQuery provides a more palatable syntax, with similar semantics. Kinda ironic that given the problem definition no solution has been provided on XQuery or XSLT yet, the widely used domain specific languages that better suit the problem :-). I believe there's a lot of inspiration to be had from the X-family of languages. The "secret sauce" is XPath. We need a new language drawing inspiration from the tree processing of X* languages but with more modern syntax and less with a less byzantine type system (read: anything but XML Schema :-). Less angle brackets would help too! --- Bonus points: add tuples and prolog like queries to such language (thinking of SPARQL) ... now that would be something really powerful.

bmn__ 6y ago
> We need a new language drawing inspiration This exists (optics/lenses), but most programmers don't know about it. I expect this to hit mainstream programming languages a few years later. I don't know of a simple, jargon-free explanation of the concepts. WP is useless, sadly. http://enwp.org/Bidirectional_transformation http://enwp.org/Bidirectional_transformation Also see: https://news.ycombinator.com/item?id=24710565 https://news.ycombinator.com/item?id=24710565
- josevalim 6y ago
  Thanks for sharing! Solutions to this problem in the vein of jq and optics were precisely why I started the repo above.
- bradrn 6y ago
  > This exists (optics/lenses), but most programmers don't know about it. … I don't know of a simple, jargon-free explanation of the concepts. Let me have a go! I’d explain optics/lenses as giving field access as a data structure. That is, a lens is an object which describes how to access an element from a ‘larger’ value. For example, you can define _1 and _2 as lenses for accessing the first and second element respectively of a tuple: _1 :: Lens' (a,b) a _2 :: Lens' (a,b) b (Using Haskell syntax here as that’s what I know best, though I’ve simplified the types slightly.) The great advantage of having these as first-class values is that you can now manipulate them. Of course, the main things you’ll want to do with these are get and set things: > (1,2) ^. _1 1 > (1,2) & _1 .~ 3 (3,2) More interestingly, you can also use a function to modify the value to which a lens is pointing: > (1,2) & _1 %~ negate (-1,2) Most usefully, you can also compose lenses. For instance, to get the second element of the first element of a nested tuple, you can compose _2 and _1 using dot notation: _1._2 :: Lens' ((a,b),c) b Or, for a more realistic example, here’s a lens which accesses the ‘numSeen’ field of the value corresponding to key "keyToIncrement": (ix "keyToIncrement")._numSeen :: Lens' (Map String MyStructure) Int (Well, strictly speaking, this is actually a traversal or a prism or something, because "keyToIncrement" might not exist, but let’s ignore that for this really simple example…) And now that you have it, you can use this new lens to do anything you want with this value: you can get it, set it, increment it, decrement it, print it, etc. Additionally, you don’t have to restrict yourself to just lenses. For example, ‘traversals’ are a generalisation of lenses which allow you to access 0, 1 or more elements, rather than restricting access to just one element at a time. For instance, you can use ‘both’ to transform, well, both elements of a tuple: > (1,2) & both 5~ negate (-1,-2) Or you can use ‘traversed’ to access each element of, say, a list: > [1,2,3,4,5] & traversed .~ 0 [0,0,0,0,0] Of course, there are other ways of doing each of these. If you happen to be working with mutable values, you can sometimes use dot notation to access deeply nested fields. Some usecases of ‘traversed’ can be replaced by a map. However, there really is no comparable substitute for lenses when working with deeply nested immutable structures, especially ones of unknown shape.
  - alehander42 6y ago
    thanks! i think i now understood the idea
- emmanueloga_ 6y ago
  optics/lenses solve this problem in a framework that is jargon-heavy and difficult to understand, and most implementations I've seen use languages with very strict type system. The XSLT+XPath approach is more dynamic, easier to grasp (imho) and can probably be learned in an afternoon. Tradeoffs, tradeoffs... I wouldn't want to write most programs in Haskell but you could write pretty much any program in, say, JavaScript ... :-)