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Questions tagged [declarative]

Declarative programming is a paradigm of expressing the logic of a computer program or computation without explicit describing its control flow.

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Solving Tower of Hanoi declaratively (Prolog)

My professor gave this as an example of Prolog. It is a program that solves the Tower of Hanoi puzzle, where you have to move a stack of disks to another peg by moving one disk after the other, without putting a bigger disk on top of a smaller disk.…
Bart Louwers
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SQLAlchemy introspection of declarative classes

I'm writing a small sqlalchemy shim to export data from a MySQL database with some lightweight data transformations—mostly changing field names. My current script works fine but requires me to essentially describe my model twice—once in the class…
Seamus Campbell
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how to access parent component scope from a child components scope in ember?

I'm curious if this is even possible in ember. This is an easy thing to do in angular ( plunkr: http://plnkr.co/edit/O2e0ukyXdKMs4FcgKGmX?p=preview ): The goal is to make an easy to use, generic, reusable accordion api for api consumers. The api I…
davidjnelson
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how is java annotation represented in java bytecode

I tried to decompile a .class file that contains JUnit tests. I read the byte code, but I did not see any clue of the @Test annotation(it's used in the java source code). As metadata, how are annotations represented in bytecode?
Cui Pengfei 崔鹏飞
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SQLAlchemy column_property basics

I have two models: class Report(Base): __tablename__ = 'report' id = Column(Integer, primary_key=True) class ReportPhoto(Base): __tablename__ = 'report_photo' id = Column(Integer, primary_key=True) report_id = Column(Integer,…
drnextgis
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Get last inserted value from MySQL using SQLAlchemy

I've just run across a fairly vexing problem, and after testing I have found that NONE of the available answers are sufficient. I have seen various suggestions but none seem to be able to return the last inserted value for an auto_increment field…
PlaidFan
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mixing foldr with OR in Haskell (laziness?)

How can this function return true? foldr (||) False [True,undefined] => True The first fold looks like this: undefined || True , which should return an error So im guessing haskell gives priority to the lazyness of the OR function over doing…
pepe22
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Passing Jenkins environment variable in Powershell script

i would like to use a jenkins environment variable inside a power shell script.Here ${destination} is coming as null inside powershell script.Not able to identify what is the mistake i am doing.Please help # !/bin/groovy pipeline { agent { …
Ramprasad
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Processing pandas data in declarative style

I have a pandas dataframe of vehicle co-ordinates (from multiple vehicles on multiple days). For each vehicle and for each day, I do two things: either apply an algorithm to it, or filter it out of the dataset completely if it doesn't satisfy…
mchristos
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What declarative language is good at analysis of tree-like data?

I'm thinking about developing a system to perform highly parallel queries on nested (but tree-like) data. The potential users are data analysts (physicists, specifically), not programmers. For the user interface, I want to use a well-known query…
Jim Pivarski
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How to stop recursing?

Advent of Code Day 1 requires looping, in one form or another, over a long string of parentheses like ((((())(())(((()))(( etc. The idea is that ( goes up one "floor", ) goes down one floor, and the objectives are to print the first index in the…
cat
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What are the advantages of attribute based programming?

I am working with WCF RIA services and have come across a sample using attributes: [StringLength(10, ErrorMessage="Too long")] public string FirstName { get; set; } ... While attributes aren't restricted to WCF RIA, it reminded me of a question:…
Scott Davies
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Problem implementing declarative transactions

I want to implement transaction control at the function level. What i want is something like this. class MyService{ static transactional = false @Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW) public def saveCountry(){…
imran
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Decide(in Haskell) if a number is or not a palindrome without using lists

I need to check in Haskell if a four digit number is a palindrome, the problem is that I can't use lists, and in spite of having a fixed digit number, I should use recursion. I have been think on the problem and I couldn't get a solution using…
Iván Rodríguez Torres
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implement a simple C like language in Prolog?

I'm new to prolog, so this's quite a challenge to me. I'm supposed to implement a simple C like language in Prolog. the ultimate goal is to be able to execute something like this: ?-…
Hashbug
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