Merge b471f2179a into 3c1b4e752d

qsharp.html.markdown

@@ -4,7 +4,6 @@ contributors:
     - ["Vincent van Wingerden", "https://github.com/vivanwin"]
     - ["Mariia Mykhailova", "https://github.com/tcNickolas"]
     - ["Andrew Ryan Davis", "https://github.com/AndrewDavis1191"]
-    - ["Alex Hansen", "https://github.com/sezna"]
 filename: LearnQSharp.qs
 ---
 
@@ -20,20 +19,19 @@ Q# is a high-level domain-specific language which enables developers to write qu
 // The most important part of quantum programs is qubits. 
 // In Q# type Qubit represents the qubits which can be used.
 // This will allocate an array of two new qubits as the variable qs.
-operation QuantumDataTypes() : Unit {
-    use qs = Qubit[2];
+using (qs = Qubit[2]) {
 
     // The qubits have internal state that you cannot access to read or modify directly.
     // You can inspect the current state of your quantum program 
     // if you're running it on a classical simulator.
     // Note that this will not work on actual quantum hardware!
-    Std.Diagnostics.DumpMachine();
+    DumpMachine();
 
     // If you want to change the state of a qubit
     // you have to do this by applying quantum gates to the qubit.
-    H(qs[0]);   // This changes the state of the first qubit
-    // from |0⟩ (the initial state of allocated qubits)
-    // to (|0⟩ + |1⟩) / sqrt(2).
+    H(qs[0]);    // This changes the state of the first qubit 
+                // from |0⟩ (the initial state of allocated qubits) 
+                // to (|0⟩ + |1⟩) / sqrt(2).
     // qs[1] = |1⟩; - this does NOT work, you have to manipulate a qubit by using gates.
 
     // You can apply multi-qubit gates to several qubits.
@@ -60,102 +58,97 @@ operation QuantumDataTypes() : Unit {
 /////////////////////////////////////
 // 2. Classical data types and operators
 
-function ClassicalDataTypes() : Unit {
-    // Numbers in Q# can be stored in Int, BigInt or Double.
-    let i = 1;            // This defines an Int variable i equal to 1
-    let bi = 1L;          // This defines a BigInt variable bi equal to 1
-    let d = 1.0;          // This defines a Double variable d equal to 1
+// Numbers in Q# can be stored in Int, BigInt or Double.
+let i = 1;            // This defines an Int variable i equal to 1
+let bi = 1L;          // This defines a BigInt variable bi equal to 1
+let d = 1.0;          // This defines a Double variable d equal to 1
 
-    // Arithmetic is done as expected, as long as the types are the same
-    let n = 2 * 10;                // = 20
-    // Q# does not have implicit type cast,
-    // so to perform arithmetic on values of different types,
-    // you need to cast type explicitly
-    let nd = Std.Convert.IntAsDouble(2) * 1.0; // = 20.0
+// Arithmetic is done as expected, as long as the types are the same
+let n = 2 * 10;                // = 20
+// Q# does not have implicit type cast, 
+// so to perform arithmetic on values of different types, 
+// you need to cast type explicitly
+let nd = IntAsDouble(2) * 1.0; // = 20.0
 
-    // Boolean type is called Bool
-    let trueBool = true;
-    let falseBool = false;
+// Boolean type is called Bool
+let trueBool = true;
+let falseBool = false;
 
-    // Logic operators work as expected
-    let andBool = true and false;
-    let orBool = true or false;
-    let notBool = not false;
+// Logic operators work as expected
+let andBool = true and false;
+let orBool = true or false;
+let notBool = not false;
 
-    // Strings
-    let str = "Hello World!";
+// Strings
+let str = "Hello World!";
 
-    // Equality is ==
-    let x = 10 == 15; // is false
+// Equality is ==
+let x = 10 == 15; // is false
 
-    // Range is a sequence of integers and can be defined like: start..step..stop
-    let xi = 1..2..7; // Gives the sequence 1,3,5,7
+// Range is a sequence of integers and can be defined like: start..step..stop
+let xi = 1..2..7; // Gives the sequence 1,3,5,7
 
-    // Assigning new value to a variable:
-    // by default all Q# variables are immutable;
-    // if the variable was defined using let, you cannot reassign its value.
+// Assigning new value to a variable:
+// by default all Q# variables are immutable;
+// if the variable was defined using let, you cannot reassign its value.
 
-    // When you want to make a variable mutable, you have to declare it as such,
-    // and use the set word to update value
-    mutable xii = true;
-    set xii = false;
+// When you want to make a variable mutable, you have to declare it as such, 
+// and use the set word to update value
+mutable xii = true;
+set xii = false;
 
-    // You can create an array for any data type like this
-    let xiii = [0.0, size = 10];
+// You can create an array for any data type like this
+let xiii = new Double[10];
 
-    // Getting an element from an array
-    let xiv = xiii[8];
+// Getting an element from an array 
+let xiv = xiii[8];
 
-    // Assigning a new value to an array element
-    mutable xv = [0.0, size = 10];
-    set xv w/= 5 <- 1.0;
-}
+// Assigning a new value to an array element
+mutable xv = new Double[10];
+set xv w/= 5 <- 1;
 
 
 /////////////////////////////////////
 // 3. Control flow
 
-operation ControlFlow() : Unit {
-    let a = 1;
-    // If expressions support a true branch, elif, and else.
-    if (a == 1) {
-        // ...
-    } elif (a == 2) {
-        // ...
-    } else {
-        // ...
-    }
-    use qubits = Qubit[2];
-
-    // For loops can be used to iterate over an array
-    for qubit in qubits {
-        X(qubit);
-    }
-
-    // Regular for loops can be used to iterate over a range of numbers
-    for index in 0..Length(qubits) - 1 {
-        X(qubits[index]);
-    }
-
-    // While loops are restricted for use in classical context only
-    mutable index = 0;
-    while (index < 10) {
-        set index += 1;
-    }
-
-    let success_criteria = true;
-    // Quantum equivalent of a while loop is a repeat-until-success loop.
-    // Because of the probabilistic nature of quantum computing sometimes
-    // you want to repeat a certain sequence of operations
-    // until a specific condition is achieved; you can use this loop to express this.
-    repeat {
-        // Your operation here
-    } until (success_criteria) // This could be a measurement to check if the state is reached
-    fixup {
-        // Resetting to the initial conditions, if required
-    }
+// If structures work a little different than most languages
+if (a == 1) {
+    // ...
+} elif (a == 2) {
+    // ... 
+} else {
+    // ...
 }
 
+// Foreach loops can be used to iterate over an array
+for (qubit in qubits) {
+    X(qubit);
+}
+
+// Regular for loops can be used to iterate over a range of numbers
+for (index in 0 .. Length(qubits) - 1) {
+    X(qubits[index]);
+}
+
+// While loops are restricted for use in classical context only
+mutable index = 0;
+while (index < 10) {
+    set index += 1;
+}
+
+// Quantum equivalent of a while loop is a repeat-until-success loop.
+// Because of the probabilistic nature of quantum computing sometimes
+// you want to repeat a certain sequence of operations 
+// until a specific condition is achieved; you can use this loop to express this.
+repeat {
+    // Your operation here
+}
+until (success criteria) // This could be a measurement to check if the state is reached
+fixup {
+    // Resetting to the initial conditions, if required
+}
+
+
 /////////////////////////////////////
 // 4. Putting it all together
 
@@ -168,7 +161,7 @@ operation ApplyXGate(source : Qubit) : Unit {
 // adjoint and controlled variants of it. 
 // The easiest way to do that is to add "is Adj + Ctl" after Unit. 
 // This will tell the compiler to generate the variants automatically.
-operation ApplyXGateCA(source : Qubit) : Unit is Adj + Ctl {
+operation ApplyXGateCA (source : Qubit) : Unit is Adj + Ctl {
     X(source);
 }
 
@@ -176,21 +169,20 @@ operation ApplyXGateCA(source : Qubit) : Unit is Adj + Ctl {
 
 
 // To run Q# code, you can put @EntryPoint() before the operation you want to run first
+@EntryPoint()
 operation XGateDemo() : Unit {
-    use q = Qubit();
-    ApplyXGate(q);
+    using (q = Qubit()) {
+        ApplyXGate(q);
+    }
 }
 
 // Here is a simple example: a quantum random number generator. 
 // We will generate a classical array of random bits using quantum code.
-// Callables (functions or operations) named `Main` are used as entry points.
-operation Main() : Unit {
-    mutable bits = [0, size = 5];                // Array we'll use to store bits
-    use q  = Qubit();
-    {
-        // Allocate a qubit
-        for i in 0..4 {
-            // Generate each bit independently
+@EntryPoint()
+operation QRNGDemo() : Unit {
+    mutable bits = new Int[5];                // Array we'll use to store bits
+    using (q = Qubit()) {                     // Allocate a qubit
+        for (i in 0 .. 4) {                   // Generate each bit independently
             H(q);                             // Hadamard gate sets equal superposition
             let result = M(q);                // Measure qubit gets 0|1 with 50/50 prob
             let bit = result == Zero ? 0 | 1; // Convert measurement result to integer
@@ -204,6 +196,9 @@ operation Main() : Unit {
 
 ## Further Reading
 
-The Quantum Katas ([repo](https://github.com/microsoft/qsharp/tree/main/katas) [hosted tutorials](https://quantum.microsoft.com/en-us/tools/quantum-katas) offer great self-paced tutorials and programming exercises to learn quantum computing and Q#. 
+The [Quantum Katas][1] offer great self-paced tutorials and programming exercises to learn quantum computing and Q#. 
 
-[Q# Documentation](https://docs.microsoft.com/quantum/) is official Q# documentation, including language reference and user guides.
+[Q# Documentation][2] is official Q# documentation, including language reference and user guides.
+
+[1]: https://github.com/microsoft/QuantumKatas
+[2]: https://docs.microsoft.com/quantum/