lazy-evaluation Questions
3
Solved
The object returned by delay in Scheme is "a promise", but promises are not considered to be a type (so there is no promise? procedure, and it's not listed as a type in R5RS or R6RS).
Is there a s...
Magnusson asked 23/9, 2010 at 10:37
1
Solved
Recently I've been trying to understand what, exactly, is forced by GHC upon the evaluation of seq. Suppose I save the below definitions:
f :: Int -> [Int] -> [Int]
f = \n -> \ns -> if ...
Sherrell asked 18/9 at 19:41
3
Is it possibile to have an java.util.Optional which is evaluated only if needed?
I need to pass an Optional to a method (of an API that I cannot change), and this method may or may not make use th...
Gulch asked 1/6, 2017 at 14:59
5
I am using SLF4J with Logback in a Spring Boot application. I was interested in using lazy logging and after some research, I came up with this solution.
This works as expected and does not invoke...
Deuteronomy asked 15/4, 2020 at 10:15
5
Solved
I'm working on a homework assignment where we are asked to implement an evaluation strategy called "call by name" in a certain language that we developed (using Scheme).
We were given an example ...
Beardsley asked 3/6, 2010 at 2:34
31
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I am trying to read a large file one line at a time. I found a question on Quora that dealt with the subject but I'm missing some connections to make the whole thing fit together.
var Lazy=requir...
Trudi asked 27/5, 2011 at 18:49
6
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I am an absolute newbie in Haskell yet trying to understand how it works.
I want to write my own lazy list of integers such as [1,2,3,4,5...].
For list of ones I have written
ones = 1 : ones
a...
Granddad asked 21/3, 2010 at 13:3
4
I would like to try out lazy expression evaluation, but I do not want to dive into Haskel right now. Please, can you help to find what other languages have this feature?
Hamiltonian asked 19/12, 2013 at 7:26
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Just curious: In Kotlin, I would love to get some val that can be initialized by lazy, but with a parameter. That's because I need something that's created very late in order to initialize it.
Spe...
Subduct asked 25/1, 2018 at 12:41
1
I have a space leak in my Haskell programm, I could pinpoint it to a minimal example as follows. I would expect the following code (albeit not terminating but I don't care) to run in constant memor...
Jaco asked 14/12, 2023 at 21:9
9
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Let's say I have this dictionary in python, defined at the module level (mysettings.py):
settings = {
'expensive1' : expensive_to_compute(1),
'expensive2' : expensive_to_compute(2),
...
}
I w...
Johnathon asked 21/5, 2013 at 11:53
2
Solved
I thought I understood laziness well until I came up with the following code, which yields a <<loop>> error.
weird = ([1],[2]) <> weird
main = print (head $ fst weird)
Intuitivel...
Gastrotrich asked 1/11, 2023 at 18:26
1
Set up:
Similar to this question on a MSDN forum, I have a measure that switches between various other measures (some of them much more complex than others). The measure looks like this (my actual ...
Skirl asked 14/5, 2020 at 19:8
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A lot of times, I have a big dataframe df to hold the basic data, and need to create many more columns to hold the derivative data calculated by basic data columns.
I can do that in Pandas like:
...
Pipestone asked 26/10, 2013 at 10:20
5
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One minor annoyance with dict.setdefault is that it always evaluates its second argument (when given, of course), even when the first argument is already a key in the dictionary.
For example:
impor...
Canoodle asked 8/7, 2013 at 17:50
3
I have a situation for Ruby, where an object is possibly necessary to be created, but it is not sure. And as the creation of the object might be costly I am not too eager creating it. I think this ...
Khmer asked 17/3, 2010 at 10:26
3
Solved
[1, 2, 3, -1, -2].filter({ $0 > 0 }).count // => 3
[1, 2, 3, -1, -2].lazy.filter({ $0 > 0 }).count // => 3
What is the advantage of adding lazy to the second statement. As per my und...
Serrate asked 19/8, 2018 at 11:13
4
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I have a question about using ugettext and gettext_lazy() for translations.
I learned that in models I should use gettext_lazy(), while in views ugettext.
But are there any other places, where I sh...
Adham asked 12/11, 2010 at 1:6
10
Solved
When I try to access to my app, I'm getting the following error below:
AppRegistryNotReady: The translation infrastructure cannot be
initialized before the apps registry is ready. Check that you d...
Earldom asked 24/12, 2014 at 0:59
2
Solved
Both 1 and "hello" are in normal form, thus are not thunks. So why does GHCi show that "hello" is a thunk?
ghci> x = 1::Int
ghci> :sprint x
x = 1
ghci> x = "hello...
Boaster asked 16/5, 2023 at 13:9
1
Solved
The wikibook says that: in this expression
let z = (length [1..5], reverse "olleh") in ...
z is a thunk.
But this stackoverflow post says that the outermost layer of z is the data constr...
Orangewood asked 16/5, 2023 at 11:49
2
Solved
Python's any and all built-in functions are supposed to short-circuit, like the logical operators or and and do.
However, suppose we have a function definition like so:
def func(s):
print(s)
retu...
Lurcher asked 27/9, 2020 at 16:28
2
Solved
I was having trouble when using foo.value_or(bar()) in my code, because I wasn't expecting the function bar() to be called when the optional variable foo had a value. I've since found this question...
Jelly asked 17/6, 2022 at 4:1
2
Solved
I love using np.fromiter from numpy because it is a resource-lazy way to build np.array objects. However, it seems like it doesn't support multidimensional arrays, which are quite useful as well.
...
Orchidectomy asked 1/12, 2015 at 10:47
4
How can I make a lazy list representing a sequence of doubling numbers? Example:
1 2 4 8 16 32
Guardhouse asked 27/10, 2009 at 16:17
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