CLP(FD) constraints are provided by all serious Prolog implementations. They allow us to reason about integers in a pure way.
?- X #= 1 + 2.
X = 3.
?- 5 #= Y + 2.
Y = 3.
Prolog itself can be considered as CLP(H): Constraint Logic Programming over Herbrand terms. With this perspective, a Prolog program posts constraints over terms. For example:
?- X = f(Y), Y = a.
X = f(a),
Y = a.
Sometimes you want to destructure key under a map which might not be present in the map, but you want a default value for the destructured value. You can do that this way:
(def my-map {:a 3 :b 4})
(let [{a :a
b :b
:keys [c d]
:or {a 1
c 2}} my-map]
(println ...
Predicates that reason about instantiations are called meta-logical. Examples are:
var/1
ground/1
integer/1
These predicates are outside the realm of pure monotonic logic programs, because they break properties like commutativity of conjunction.
Other predicates that are meta-logical includ...
CLP(FD) constraints are completely pure relations. They can be used in all directions for declarative integer arithmetic:
?- X #= 1+2.
X = 3.
?- 3 #= Y+2.
Y = 1.
Our example array:
arr=(a b c d e f)
Using a for..in loop:
for i in "${arr[@]}"; do
echo "$i"
done
2.04
Using C-style for loop:
for ((i=0;i<${#arr[@]};i++)); do
echo "${arr[$i]}"
done
Using while loop:
i=0
while [ $i -lt ${#arr[@]} ]; do...
The MEDIAN function since Oracle 10g is an easy to use aggregation function:
SELECT MEDIAN(SAL)
FROM EMP
It returns the median of the values
Works on DATETIME values too.
The result of MEDIAN is computed by first ordering the rows. Using N as the number of rows in the group, Oracle calcula...
Following code will release the lock. There will be no problem. Behind the scenes lock statement works as try finally
lock(locker)
{
throw new Exception();
}
More can be seen in the C# 5.0 Specification:
A lock statement of the form
lock (x) ...
where x is an expression of a referenc...
Partial application means calling a function with less arguments than it has and saving the result as another function (that waits for the rest of the arguments).
multiplyBy: Int -> Int -> Int
multiplyBy x y =
x * y
multiplyByTwo : Int -> Int -- one Int has disappeared! we ...
Given a C++ source file main.cpp defining a main() function, an accompanying CMakeLists.txt file (with the following content) will instruct CMake to generate the appropriate build instructions for the current system and default C++ compiler.
main.cpp (C++ Hello World Example)
#include <iostream...
Enum classes as any other classes can have a constructor and be initialized
enum class Color(val rgb: Int) {
RED(0xFF0000),
GREEN(0x00FF00),
BLUE(0x0000FF)
}
The routing configuration is included in your app/config/config.yml file, by default the app/config/routing.yml file.
From there you can link to your own routing configuration in a bundle
# app/config/routing.yml
app:
resource: "@AppBundle/Resources/config/routing.yml"
It migh...
A browser's debugging console can be used in order to print simple messages. This debugging or web console can be directly opened in the browser (F12 key in most browsers – see Remarks below for further information) and the log method of the console Javascript object can be invoked by typing the fol...
