An example of each, using javascript since everybody can read it. Please don’t use this code in production, use a real library, there are plenty of good ones. var a, b, c, async_obj; // assume exist // CommonJS – for reference purposes try { async_obj.asyncMethod(a, b, c, function (error1, result1) { if (error1) { console.error(error1); … Read more
In addition to user239558’s answer, and in response to your comment there, I’d like to point out some tools that allow you to inspect the heap representation of your value, find answers to questions like this yourself and to see the effect of optimizations and different ways of compiling. ghc-datasize tells you the size of … Read more
Because (,) is a constructor, the difference makes no difference to Haskell’s semantics (:sprint gives access to internal thunk implementation details so doesn’t count.) So this is a question of which optimizations and trade-offs GHC does when compiling (x,x) in different positions. Someone else may know the precise reason in these cases.
Official answer It’s none of your business. Strictly implementation detail of your compiler. Short answer Yes. Longer answer To the Haskell program itself, the answer is always yes, but the compiler can and will do things differently if it finds out that it can get away with it, for performance reasons. For example, for ”’add … Read more
From the blog post @Lambdageek linked, the GHC Commentary and the GHC User’s Guide I piece together the following: GHC tries to prevent reevaluating thunks, but because true locking between threads is expensive, and thunks are usually pure and so harmless to reevaluate, it normally does so in a sloppy manner, with a small chance … Read more
A thunk usually refers to a small piece of code that is called as a function, does some small thing, and then JUMPs to another location (usually a function) instead of returning to its caller. Assuming the JUMP target is a normal function, when it returns, it will return to the thunk’s caller. Thunks can … Read more