5 ms·

Though unlike Haskell, it is strict.

• asattarmd 10y ago
  Strict by default. You can make it lazy easily.
• clacke2 10y ago
  The next Haskell will be strict -- Simon Peyton Jones http://www.cs.nott.ac.uk/%7Egmh/appsem-slides/peytonjones.ppt http://www.cs.nott.ac.uk/%7Egmh/appsem-slides/peytonjones.pp... /via https://news.ycombinator.com/item?id=1924061 https://news.ycombinator.com/item?id=1924061
  • kobeya 10y ago
    Yes, but not because laziness was a technical failure, but for something more resembling PR reasons. Haskell's laziness by default ends up being a large stumbling block for many developers not used to thinking in that way. Although I understand why Idris is strict by default, there is a part of me that dies a little from that understanding :(
    • mafribe 10y ago
      The main problem with laziness is that, according to SPJ "[l]aziness makes it much, much harder to reason about performance, especially space."
      • willtim 10y ago
        Of course, lazy-by-default also brings many advantages: http://augustss.blogspot.co.uk/2011/05/more-points-for-lazy-evaluation-in.html http://augustss.blogspot.co.uk/2011/05/more-points-for-lazy-...
        • deleted 10y ago
          [deleted]
    • solidsnack9000 10y ago
      It's not so much a PR failure, as an ergonomics issue -- making laziness the default makes it too easy for people to create performance problems for themselves. Haskell's laziness undoubtedly works and is useful; you might say it was Haskell's strictness that needed improving.
• pjmlp 10y ago
  Haskell is just lazy by default, you can make code explicitly strict. Just like other languages are strict by default, but can be made lazy via sequences, streams, generators,... It is just a matter which defaults might be better for a given application.
  • vram22 10y ago
    What does strict mean in this context? I don't know too much about these concepts. I think lazy means only evaluated when needed, like in generators (using Python as an example, which I know - I don't know Haskell or Idris). And I thought (from what little I've read), that the opposite of lazy evaluation was eager evaluation. So in Python at least, an example of eager vs. lazy would be returning a list vs. returning a generator from a function. For the former (list), the whole list would have to be created/populated and then returned (thereby occupying memory for the duration of its use), whereas for the latter (generator), items from it would only be yielded on demand, e.g. one at a time, when next() is called, or when the generator is iterated over, and so would not use as much memory as needed for the sum of the sizes of the items in the list. So where does strict fit in here? Feel free to point if I've got any of the above wrong. Update: Thanks for the replies, people.
    • chongli 10y ago
      Strict evaluation is a synonym for eager evaluation. In Haskell, the primary mechanism for inducing evaluation is the case expression (if/then/else and pattern matching are syntactic sugar for case). Thunks (lazy expressions) in Haskell are created with let and then forced with case. It's very straightforward at the most basic level, there's just a lot of abstraction built on top of it that can obscure what's going on.
    • laszlokorte 10y ago
      strict is same as eager and non-strict is same as lazy https://wiki.haskell.org/Lazy_vs._non-strict https://wiki.haskell.org/Lazy_vs._non-strict
    • mrkgnao 10y ago
      I wrote this a while back. You might find it of some use. https://news.ycombinator.com/item?id=13907573 https://news.ycombinator.com/item?id=13907573