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diff --git a/chapel.html.markdown b/chapel.html.markdown index 4619785e..68ce49cd 100644 --- a/chapel.html.markdown +++ b/chapel.html.markdown @@ -3,89 +3,113 @@ language: chapel filename: learnchapel.chpl contributors: - ["Ian J. Bertolacci", "http://www.cs.colostate.edu/~ibertola/"] + - ["Ben Harshbarger", "http://github.com/benharsh/"] --- You can read all about Chapel at [Cray's official Chapel website](http://chapel.cray.com). -In short, Chapel is an open-source, high-productivity, parallel-programming language in development at Cray Inc., and is designed to run on multi-core PCs as well as multi-kilocore supercomputers. +In short, Chapel is an open-source, high-productivity, parallel-programming +language in development at Cray Inc., and is designed to run on multi-core PCs +as well as multi-kilocore supercomputers. More information and support can be found at the bottom of this document. ```chapel // Comments are C-family style + // one line comment /* - multi-line comment + multi-line comment */ // Basic printing -write( "Hello, " ); -writeln( "World!" ); + +write("Hello, "); +writeln("World!"); + // write and writeln can take a list of things to print. -// each thing is printed right next to each other, so include your spacing! -writeln( "There are ", 3, " commas (\",\") in this line of code" ); -// Different output channels -stdout.writeln( "This goes to standard output, just like plain writeln() does"); -stderr.writeln( "This goes to standard error" ); +// Each thing is printed right next to the others, so include your spacing! +writeln("There are ", 3, " commas (\",\") in this line of code"); + +// Different output channels: +stdout.writeln("This goes to standard output, just like plain writeln() does"); +stderr.writeln("This goes to standard error"); + // Variables don't have to be explicitly typed as long as // the compiler can figure out the type that it will hold. -var myVar = 10; // 10 is an int, so myVar is implicitly an int +// 10 is an int, so myVar is implicitly an int +var myVar = 10; myVar = -10; var mySecondVar = myVar; -// var anError; // this would be a compile-time error. +// var anError; would be a compile-time error. -// We can (and should) explicitly type things +// We can (and should) explicitly type things. var myThirdVar: real; var myFourthVar: real = -1.234; myThirdVar = myFourthVar; +// Types + // There are a number of basic types. var myInt: int = -1000; // Signed ints var myUint: uint = 1234; // Unsigned ints var myReal: real = 9.876; // Floating point numbers var myImag: imag = 5.0i; // Imaginary numbers var myCplx: complex = 10 + 9i; // Complex numbers -myCplx = myInt + myImag ; // Another way to form complex numbers +myCplx = myInt + myImag; // Another way to form complex numbers var myBool: bool = false; // Booleans var myStr: string = "Some string..."; // Strings +var singleQuoteStr = 'Another string...'; // String literal with single quotes -// Some types can have sizes +// Some types can have sizes. var my8Int: int(8) = 10; // 8 bit (one byte) sized int; var my64Real: real(64) = 1.516; // 64 bit (8 bytes) sized real -// Typecasting +// Typecasting. var intFromReal = myReal : int; var intFromReal2: int = myReal : int; -// consts are constants, they cannot be changed after set in runtime. +// Type aliasing. +type chroma = int; // Type of a single hue +type RGBColor = 3*chroma; // Type representing a full color +var black: RGBColor = (0,0,0); +var white: RGBColor = (255, 255, 255); + +// Constants and Parameters + +// A const is a constant, and cannot be changed after set in runtime. const almostPi: real = 22.0/7.0; -// params are constants whose value must be known statically at compile-time -// Their value cannot be changed. +// A param is a constant whose value must be known statically at +// compile-time. param compileTimeConst: int = 16; -// The config modifier allows values to be set at the command line -// and is much easier than the usual getOpts debacle -// config vars and consts can be changed through the command line at run time +// The config modifier allows values to be set at the command line. +// Set with --varCmdLineArg=Value or --varCmdLineArg Value at runtime. config var varCmdLineArg: int = -123; config const constCmdLineArg: int = 777; -// Set with --VarName=Value or --VarName Value at run time -// config params can be set/changed at compile-time +// config param can be set at compile-time. +// Set with --set paramCmdLineArg=value at compile-time. config param paramCmdLineArg: bool = false; -// Set config with --set paramCmdLineArg=value at compile-time -writeln( varCmdLineArg, ", ", constCmdLineArg, ", ", paramCmdLineArg ); +writeln(varCmdLineArg, ", ", constCmdLineArg, ", ", paramCmdLineArg); -// refs operate much like a reference in C++ +// References + +// ref operates much like a reference in C++. In Chapel, a ref cannot +// be made to alias a variable other than the variable it is initialized with. +// Here, refToActual refers to actual. var actual = 10; -ref refToActual = actual; // refToActual refers to actual -writeln( actual, " == ", refToActual ); // prints the same value +ref refToActual = actual; +writeln(actual, " == ", refToActual); // prints the same value actual = -123; // modify actual (which refToActual refers to) -writeln( actual, " == ", refToActual ); // prints the same value +writeln(actual, " == ", refToActual); // prints the same value refToActual = 99999999; // modify what refToActual refers to (which is actual) -writeln( actual, " == ", refToActual ); // prints the same value +writeln(actual, " == ", refToActual); // prints the same value + +// Operators -// Math operators +// Math operators: var a: int, thisInt = 1234, thatInt = 5678; a = thisInt + thatInt; // Addition a = thisInt * thatInt; // Multiplication @@ -94,252 +118,259 @@ a = thisInt / thatInt; // Division a = thisInt ** thatInt; // Exponentiation a = thisInt % thatInt; // Remainder (modulo) -// Logical Operators +// Logical operators: var b: bool, thisBool = false, thatBool = true; b = thisBool && thatBool; // Logical and b = thisBool || thatBool; // Logical or b = !thisBool; // Logical negation -// Relational Operators +// Relational operators: b = thisInt > thatInt; // Greater-than b = thisInt >= thatInt; // Greater-than-or-equal-to b = thisInt < a && a <= thatInt; // Less-than, and, less-than-or-equal-to b = thisInt != thatInt; // Not-equal-to b = thisInt == thatInt; // Equal-to -// Bitwise operations +// Bitwise operators: a = thisInt << 10; // Left-bit-shift by 10 bits; a = thatInt >> 5; // Right-bit-shift by 5 bits; a = ~thisInt; // Bitwise-negation a = thisInt ^ thatInt; // Bitwise exclusive-or -// Compound assignment operations -a += thisInt; // Addition-equals ( a = a + thisInt;) -a *= thatInt; // Times-equals ( a = a * thatInt; ) -b &&= thatBool; // Logical-and-equals ( b = b && thatBool; ) -a <<= 3; // Left-bit-shift-equals ( a = a << 10; ) -// and many, many more. -// Unlike other C family languages there are no -// pre/post-increment/decrement operators like -// ++j, --j, j++, j-- - -// Swap operator +// Compound assignment operators: +a += thisInt; // Addition-equals (a = a + thisInt;) +a *= thatInt; // Times-equals (a = a * thatInt;) +b &&= thatBool; // Logical-and-equals (b = b && thatBool;) +a <<= 3; // Left-bit-shift-equals (a = a << 10;) + +// Unlike other C family languages, there are no +// pre/post-increment/decrement operators, such as: +// +// ++j, --j, j++, j-- + +// Swap operator: var old_this = thisInt; var old_that = thatInt; thisInt <=> thatInt; // Swap the values of thisInt and thatInt -writeln( (old_this == thatInt) && (old_that == thisInt) ); +writeln((old_this == thatInt) && (old_that == thisInt)); + +// Operator overloads can also be defined, as we'll see with procedures. -// Operator overloads can also be defined, as we'll see with procedures +// Tuples -// Tuples can be of the same type -var sameTup: 2*int = (10,-1); +// Tuples can be of the same type or different types. +var sameTup: 2*int = (10, -1); var sameTup2 = (11, -6); -// or different types var diffTup: (int,real,complex) = (5, 1.928, myCplx); -var diffTupe2 = ( 7, 5.64, 6.0+1.5i ); +var diffTupe2 = (7, 5.64, 6.0+1.5i); -// Accessed using array bracket notation -// However, tuples are all 1-indexed -writeln( "(", sameTup[1], ",", sameTup[2], ")" ); -writeln( diffTup ); +// Tuples can be accessed using square brackets or parentheses, and are +// 1-indexed. +writeln("(", sameTup[1], ",", sameTup(2), ")"); +writeln(diffTup); // Tuples can also be written into. -diffTup[1] = -1; +diffTup(1) = -1; -// Can expand tuple values into their own variables +// Tuple values can be expanded into their own variables. var (tupInt, tupReal, tupCplx) = diffTup; -writeln( diffTup == (tupInt, tupReal, tupCplx) ); +writeln(diffTup == (tupInt, tupReal, tupCplx)); -// Useful for writing a list of variables ( as is common in debugging) -writeln( (a,b,thisInt,thatInt,thisBool,thatBool) ); +// They are also useful for writing a list of variables, as is common in debugging. +writeln((a,b,thisInt,thatInt,thisBool,thatBool)); -// Type aliasing -type chroma = int; // Type of a single hue -type RGBColor = 3*chroma; // Type representing a full color -var black: RGBColor = ( 0,0,0 ); -var white: RGBColor = ( 255, 255, 255 ); +// Control Flow -// If-then-else works just like any other C-family language +// if - then - else works just like any other C-family language. if 10 < 100 then - writeln( "All is well" ); + writeln("All is well"); if -1 < 1 then - writeln( "Continuing to believe reality" ); + writeln("Continuing to believe reality"); else - writeln( "Send mathematician, something's wrong" ); + writeln("Send mathematician, something's wrong"); -if ( 10 > 100 ) { - writeln( "Universe broken. Please reboot universe." ); +// You can use parentheses if you prefer. +if (10 > 100) { + writeln("Universe broken. Please reboot universe."); } -if ( a % 2 == 0 ) { - writeln( a, " is even." ); +if a % 2 == 0 { + writeln(a, " is even."); } else { - writeln( a, " is odd." ); + writeln(a, " is odd."); } -if ( a % 3 == 0 ) { - writeln( a, " is even divisible by 3." ); -} else if ( a % 3 == 1 ){ - writeln( a, " is divided by 3 with a remainder of 1." ); +if a % 3 == 0 { + writeln(a, " is even divisible by 3."); +} else if a % 3 == 1 { + writeln(a, " is divided by 3 with a remainder of 1."); } else { - writeln( b, " is divided by 3 with a remainder of 2." ); + writeln(b, " is divided by 3 with a remainder of 2."); } -// Ternary: if-then-else in a statement -var maximum = if ( thisInt < thatInt ) then thatInt else thisInt; +// Ternary: if - then - else in a statement. +var maximum = if thisInt < thatInt then thatInt else thisInt; -// Select statements are much like switch statements in other languages -// However, Select statements don't cascade like in C or Java +// select statements are much like switch statements in other languages. +// However, select statements don't cascade like in C or Java. var inputOption = "anOption"; -select( inputOption ){ - when "anOption" do writeln( "Chose 'anOption'" ); +select inputOption { + when "anOption" do writeln("Chose 'anOption'"); when "otherOption" { - writeln( "Chose 'otherOption'" ); - writeln( "Which has a body" ); + writeln("Chose 'otherOption'"); + writeln("Which has a body"); } otherwise { - writeln( "Any other Input" ); - writeln( "the otherwise case doesn't need a do if the body is one line" ); + writeln("Any other Input"); + writeln("the otherwise case doesn't need a do if the body is one line"); } } -// While and Do-While loops are basically the same in every language. +// while and do-while loops also behave like their C counterparts. var j: int = 1; var jSum: int = 0; -while( j <= 1000 ){ +while (j <= 1000) { jSum += j; j += 1; } -writeln( jSum ); +writeln(jSum); -// Do-While loop -do{ +do { jSum += j; j += 1; -}while( j <= 10000 ); -writeln( jSum ); +} while (j <= 10000); +writeln(jSum); -// For loops are much like those in python in that they iterate over a range. -// Ranges themselves are types, and can be stuffed into variables -// (more about that later) -for i in 1..10 do write( i , ", ") ; -writeln( ); +// for loops are much like those in python in that they iterate over a +// range. Ranges (like the 1..10 expression below) are a first-class object +// in Chapel, and as such can be stored in variables. +for i in 1..10 do write(i, ", "); +writeln(); var iSum: int = 0; for i in 1..1000 { iSum += i; } -writeln( iSum ); +writeln(iSum); for x in 1..10 { for y in 1..10 { - write( (x,y), "\t" ); + write((x,y), "\t"); } - writeln( ); + writeln(); } // Ranges and Domains -// For-loops and arrays both use ranges and domains to -// define an index set that can be iterated over. -// Ranges are single dimensional -// Domains can be multi-dimensional and can -// represent indices of different types as well. -// They are first-class citizen types, and can be assigned into variables + +// For-loops and arrays both use ranges and domains to define an index set that +// can be iterated over. Ranges are single dimensional integer indices, while +// domains can be multi-dimensional and represent indices of different types. + +// They are first-class citizen types, and can be assigned into variables. var range1to10: range = 1..10; // 1, 2, 3, ..., 10 var range2to11 = 2..11; // 2, 3, 4, ..., 11 -var rangeThistoThat: range = thisInt..thatInt; // using variables -var rangeEmpty: range = 100..-100 ; // this is valid but contains no indices +var rangeThisToThat: range = thisInt..thatInt; // using variables +var rangeEmpty: range = 100..-100; // this is valid but contains no indices -// Ranges can be unbounded -var range1toInf: range(boundedType=BoundedRangeType.boundedLow) = 1.. ; -// 1, 2, 3, 4, 5, ... -// Note: the range(boundedType= ... ) is only -// necessary if we explicitly type the variable +// Ranges can be unbounded. +var range1toInf: range(boundedType=BoundedRangeType.boundedLow) = 1.. ; // 1, 2, 3, 4, 5, ... +var rangeNegInfTo1 = ..1; // ..., -4, -3, -2, -1, 0, 1 -var rangeNegInfto1 = ..1; // ..., -4, -3, -2, -1, 0, 1 - -// Ranges can be strided using the 'by' operator. +// Ranges can be strided (and reversed) using the by operator. var range2to10by2: range(stridable=true) = 2..10 by 2; // 2, 4, 6, 8, 10 -// Note: the range(stridable=true) is only -// necessary if we explicitly type the variable +var reverse2to10by2 = 2..10 by -2; // 10, 8, 6, 4, 2 + +var trapRange = 10..1 by -1; // Do not be fooled, this is still an empty range +writeln("Size of range '", trapRange, "' = ", trapRange.length); -// Use by to create a reverse range -var reverse2to10by2 = 10..2 by -2; // 10, 8, 6, 4, 2 +// Note: range(boundedType= ...) and range(stridable= ...) are only +// necessary if we explicitly type the variable. -// The end point of a range can be determined using the count (#) operator +// The end point of a range can be determined using the count (#) operator. var rangeCount: range = -5..#12; // range from -5 to 6 -// Can mix operators +// Operators can be mixed. var rangeCountBy: range(stridable=true) = -5..#12 by 2; // -5, -3, -1, 1, 3, 5 -writeln( rangeCountBy ); +writeln(rangeCountBy); -// Can query properties of the range -// Print the first index, last index, number of indices, -// stride, and ask if 2 is include in the range -writeln( ( rangeCountBy.first, rangeCountBy.last, rangeCountBy.length, - rangeCountBy.stride, rangeCountBy.member( 2 ) ) ); +// Properties of the range can be queried. +// In this example, printing the first index, last index, number of indices, +// stride, and if 2 is include in the range. +writeln((rangeCountBy.first, rangeCountBy.last, rangeCountBy.length, + rangeCountBy.stride, rangeCountBy.member(2))); -for i in rangeCountBy{ - write( i, if i == rangeCountBy.last then "\n" else ", " ); +for i in rangeCountBy { + write(i, if i == rangeCountBy.last then "\n" else ", "); } -// Rectangular domains are defined using the same range syntax -// However they are required to be bounded (unlike ranges) +// Rectangular domains are defined using the same range syntax, +// but they are required to be bounded (unlike ranges). var domain1to10: domain(1) = {1..10}; // 1D domain from 1..10; var twoDimensions: domain(2) = {-2..2,0..2}; // 2D domain over product of ranges var thirdDim: range = 1..16; var threeDims: domain(3) = {thirdDim, 1..10, 5..10}; // using a range variable -// Can iterate over the indices as tuples +// Domains can also be resized +var resizedDom = {1..10}; +writeln("before, resizedDom = ", resizedDom); +resizedDom = {-10..#10}; +writeln("after, resizedDom = ", resizedDom); + +// Indices can be iterated over as tuples. for idx in twoDimensions do - write( idx , ", "); -writeln( ); + write(idx, ", "); +writeln(); -// or can deconstruct the tuple +// These tuples can also be deconstructed. for (x,y) in twoDimensions { - write( "(", x, ", ", y, ")", ", " ); + write("(", x, ", ", y, ")", ", "); } -writeln( ); +writeln(); -// Associative domains act like sets +// Associative domains act like sets. var stringSet: domain(string); // empty set of strings stringSet += "a"; stringSet += "b"; stringSet += "c"; stringSet += "a"; // Redundant add "a" stringSet -= "c"; // Remove "c" -writeln( stringSet ); +writeln(stringSet.sorted()); + +// Associative domains can also have a literal syntax +var intSet = {1, 2, 4, 5, 100}; // Both ranges and domains can be sliced to produce a range or domain with the -// intersection of indices +// intersection of indices. var rangeA = 1.. ; // range from 1 to infinity var rangeB = ..5; // range from negative infinity to 5 var rangeC = rangeA[rangeB]; // resulting range is 1..5 -writeln( (rangeA, rangeB, rangeC ) ); +writeln((rangeA, rangeB, rangeC)); var domainA = {1..10, 5..20}; var domainB = {-5..5, 1..10}; var domainC = domainA[domainB]; -writeln( (domainA, domainB, domainC) ); +writeln((domainA, domainB, domainC)); + +// Arrays -// Array are similar to those of other languages. -// Their sizes are defined using domains that represent their indices +// Arrays are similar to those of other languages. +// Their sizes are defined using domains that represent their indices. var intArray: [1..10] int; -var intArray2: [{1..10}] int; //equivalent +var intArray2: [{1..10}] int; // equivalent -// Accessed using bracket notation +// They can be accessed using either brackets or parentheses for i in 1..10 do intArray[i] = -i; -writeln( intArray ); +writeln(intArray); + // We cannot access intArray[0] because it exists outside // of the index set, {1..10}, we defined it to have. // intArray[11] is illegal for the same reason. - var realDomain: domain(2) = {1..5,1..7}; var realArray: [realDomain] real; -var realArray2: [1..5,1..7] real; // Equivalent -var realArray3: [{1..5,1..7}] real; // Equivalent +var realArray2: [1..5,1..7] real; // equivalent +var realArray3: [{1..5,1..7}] real; // equivalent for i in 1..5 { for j in realDomain.dim(2) { // Only use the 2nd dimension of the domain @@ -349,357 +380,390 @@ for i in 1..5 { } } -// Arrays have domains as members that we can iterate over +// Arrays have domains as members, and can be iterated over as normal. for idx in realArray.domain { // Again, idx is a 2*int tuple - realArray[idx] = 1 / realArray[idx[1],idx[2]]; // Access by tuple and list + realArray[idx] = 1 / realArray[idx[1], idx[2]]; // Access by tuple and list } -writeln( realArray ); +writeln(realArray); -// Can also iterate over the values of an array +// The values of an array can also be iterated directly. var rSum: real = 0; for value in realArray { rSum += value; // Read a value value = rSum; // Write a value } -writeln( rSum, "\n", realArray ); +writeln(rSum, "\n", realArray); -// Using associative domains we can create associative arrays (dictionaries) +// Associative arrays (dictionaries) can be created using associative domains. var dictDomain: domain(string) = { "one", "two" }; -var dict: [dictDomain] int = [ "one" => 1, "two" => 2 ]; -dict["three"] = 3; -for key in dictDomain do writeln( dict[key] ); +var dict: [dictDomain] int = ["one" => 1, "two" => 2]; +dict["three"] = 3; // Adds 'three' to 'dictDomain' implicitly +for key in dictDomain.sorted() do + writeln(dict[key]); + +// Arrays can be assigned to each other in a few different ways. +// These arrays will be used in the example. +var thisArray : [0..5] int = [0,1,2,3,4,5]; +var thatArray : [0..5] int; -// Arrays can be assigned to each other in different ways -var thisArray : [{0..5}] int = [0,1,2,3,4,5]; -var thatArray : [{0..5}] int; +// First, simply assign one to the other. This copies thisArray into +// thatArray, instead of just creating a reference. Therefore, modifying +// thisArray does not also modify thatArray. -// Simply assign one to the other. -// This copies thisArray into thatArray, instead of just creating a reference. -// Modifying thisArray does not also modify thatArray. thatArray = thisArray; thatArray[1] = -1; -writeln( (thisArray, thatArray) ); +writeln((thisArray, thatArray)); -// Assign a slice one array to a slice (of the same size) of the other. -thatArray[{4..5}] = thisArray[{1..2}]; -writeln( (thisArray, thatArray) ); +// Assign a slice from one array to a slice (of the same size) in the other. +thatArray[4..5] = thisArray[1..2]; +writeln((thisArray, thatArray)); -// Operation can also be promoted to work on arrays. +// Operations can also be promoted to work on arrays. 'thisPlusThat' is also +// an array. var thisPlusThat = thisArray + thatArray; -writeln( thisPlusThat ); +writeln(thisPlusThat); -// Arrays and loops can also be expressions, where loop +// Moving on, arrays and loops can also be expressions, where the loop // body's expression is the result of each iteration. var arrayFromLoop = for i in 1..10 do i; -writeln( arrayFromLoop ); +writeln(arrayFromLoop); -// An expression can result in nothing, -// such as when filtering with an if-expression +// An expression can result in nothing, such as when filtering with an if-expression. var evensOrFives = for i in 1..10 do if (i % 2 == 0 || i % 5 == 0) then i; -writeln( arrayFromLoop ); +writeln(arrayFromLoop); -// Or could be written with a bracket notation -// Note: this syntax uses the 'forall' parallel concept discussed later. -var evensOrFivesAgain = [ i in 1..10 ] if (i % 2 == 0 || i % 5 == 0) then i; +// Array expressions can also be written with a bracket notation. +// Note: this syntax uses the forall parallel concept discussed later. +var evensOrFivesAgain = [i in 1..10] if (i % 2 == 0 || i % 5 == 0) then i; -// Or over the values of the array -arrayFromLoop = [ value in arrayFromLoop ] value + 1; +// They can also be written over the values of the array. +arrayFromLoop = [value in arrayFromLoop] value + 1; -// Note: this notation can get somewhat tricky. For example: -// evensOrFives = [ i in 1..10 ] if (i % 2 == 0 || i % 5 == 0) then i; -// would break. -// The reasons for this are explained in depth when discussing zipped iterators. -// Chapel procedures have similar syntax to other languages functions. -proc fibonacci( n : int ) : int { - if ( n <= 1 ) then return n; - return fibonacci( n-1 ) + fibonacci( n-2 ); +// Procedures + +// Chapel procedures have similar syntax functions in other languages. +proc fibonacci(n : int) : int { + if n <= 1 then return n; + return fibonacci(n-1) + fibonacci(n-2); } -// Input parameters can be untyped (a generic procedure) -proc doublePrint( thing ): void { - write( thing, " ", thing, "\n"); +// Input parameters can be untyped to create a generic procedure. +proc doublePrint(thing): void { + write(thing, " ", thing, "\n"); } -// Return type can be inferred (as long as the compiler can figure it out) -proc addThree( n ) { +// The return type can be inferred, as long as the compiler can figure it out. +proc addThree(n) { return n + 3; } -doublePrint( addThree( fibonacci( 20 ) ) ); +doublePrint(addThree(fibonacci(20))); -// Can also take 'unlimited' number of parameters -proc maxOf( x ...?k ) { +// It is also possible to take a variable number of parameters. +proc maxOf(x ...?k) { // x refers to a tuple of one type, with k elements var maximum = x[1]; - for i in 2..k do maximum = if (maximum < x[i]) then x[i] else maximum; + for i in 2..k do maximum = if maximum < x[i] then x[i] else maximum; return maximum; } -writeln( maxOf( 1, -10, 189, -9071982, 5, 17, 20001, 42 ) ); +writeln(maxOf(1, -10, 189, -9071982, 5, 17, 20001, 42)); -// The ? operator is called the query operator, and is used to take -// undetermined values (like tuple or array sizes, and generic types). +// Procedures can have default parameter values, and +// the parameters can be named in the call, even out of order. +proc defaultsProc(x: int, y: real = 1.2634): (int,real) { + return (x,y); +} -// Taking arrays as parameters. -// The query operator is used to determine the domain of A. -// This is important to define the return type (if you wanted to) -proc invertArray( A: [?D] int ): [D] int{ +writeln(defaultsProc(10)); +writeln(defaultsProc(x=11)); +writeln(defaultsProc(x=12, y=5.432)); +writeln(defaultsProc(y=9.876, x=13)); + +// The ? operator is called the query operator, and is used to take +// undetermined values like tuple or array sizes and generic types. +// For example, taking arrays as parameters. The query operator is used to +// determine the domain of A. This is uesful for defining the return type, +// though it's not required. +proc invertArray(A: [?D] int): [D] int{ for a in A do a = -a; return A; } -writeln( invertArray( intArray ) ); +writeln(invertArray(intArray)); -// Procedures can have default parameter values, and -// the parameters can be named in the call, even out of order -proc defaultsProc( x: int, y: real = 1.2634 ): (int,real){ - return (x,y); +// We can query the type of arguments to generic procedures. +// Here we define a procedure that takes two arguments of +// the same type, yet we don't define what that type is. +proc genericProc(arg1 : ?valueType, arg2 : valueType): void { + select(valueType) { + when int do writeln(arg1, " and ", arg2, " are ints"); + when real do writeln(arg1, " and ", arg2, " are reals"); + otherwise writeln(arg1, " and ", arg2, " are somethings!"); + } +} + +genericProc(1, 2); +genericProc(1.2, 2.3); +genericProc(1.0+2.0i, 3.0+4.0i); + +// We can also enforce a form of polymorphism with the where clause +// This allows the compiler to decide which function to use. +// Note: That means that all information needs to be known at compile-time. +// The param modifier on the arg is used to enforce this constraint. +proc whereProc(param N : int): void + where (N > 0) { + writeln("N is greater than 0"); } -writeln( defaultsProc( 10 ) ); -writeln( defaultsProc( x=11 ) ); -writeln( defaultsProc( x=12, y=5.432 ) ); -writeln( defaultsProc( y=9.876, x=13 ) ); - -// Intent modifiers on the arguments convey how -// those arguments are passed to the procedure -// in: copy arg in, but not out -// out: copy arg out, but not in -// inout: copy arg in, copy arg out -// ref: pass arg by reference -proc intentsProc( in inarg, out outarg, inout inoutarg, ref refarg ){ - writeln( "Inside Before: ", (inarg, outarg, inoutarg, refarg) ); +proc whereProc(param N : int): void + where (N < 0) { + writeln("N is less than 0"); +} + +whereProc(10); +whereProc(-1); + +// whereProc(0) would result in a compiler error because there +// are no functions that satisfy the where clause's condition. +// We could have defined a whereProc without a where clause +// that would then have served as a catch all for all the other cases +// (of which there is only one). + +// where clauses can also be used to constrain based on argument type. +proc whereType(x: ?t) where t == int { + writeln("Inside 'int' version of 'whereType': ", x); +} + +proc whereType(x: ?t) { + writeln("Inside general version of 'whereType': ", x); +} + +whereType(42); +whereType("hello"); + +// Intents + +/* Intent modifiers on the arguments convey how those arguments are passed to the procedure. + + * in: copy arg in, but not out + * out: copy arg out, but not in + * inout: copy arg in, copy arg out + * ref: pass arg by reference +*/ +proc intentsProc(in inarg, out outarg, inout inoutarg, ref refarg) { + writeln("Inside Before: ", (inarg, outarg, inoutarg, refarg)); inarg = inarg + 100; outarg = outarg + 100; inoutarg = inoutarg + 100; refarg = refarg + 100; - writeln( "Inside After: ", (inarg, outarg, inoutarg, refarg) ); + writeln("Inside After: ", (inarg, outarg, inoutarg, refarg)); } var inVar: int = 1; var outVar: int = 2; var inoutVar: int = 3; var refVar: int = 4; -writeln( "Outside Before: ", (inVar, outVar, inoutVar, refVar) ); -intentsProc( inVar, outVar, inoutVar, refVar ); -writeln( "Outside After: ", (inVar, outVar, inoutVar, refVar) ); - -// Similarly we can define intents on the return type -// refElement returns a reference to an element of array -proc refElement( array : [?D] ?T, idx ) ref : T { - return array[ idx ]; // returns a reference to -} +writeln("Outside Before: ", (inVar, outVar, inoutVar, refVar)); +intentsProc(inVar, outVar, inoutVar, refVar); +writeln("Outside After: ", (inVar, outVar, inoutVar, refVar)); -var myChangingArray : [1..5] int = [1,2,3,4,5]; -writeln( myChangingArray ); -// Store reference to element in ref variable -ref refToElem = refElement( myChangingArray, 5 ); -writeln( refToElem ); -refToElem = -2; // modify reference which modifies actual value in array -writeln( refToElem ); -writeln( myChangingArray ); +// Similarly, we can define intents on the return type. +// refElement returns a reference to an element of array. // This makes more practical sense for class methods where references to -// elements in a data-structure are returned via a method or iterator - -// We can query the type of arguments to generic procedures -// Here we define a procedure that takes two arguments of -// the same type, yet we don't define what that type is. -proc genericProc( arg1 : ?valueType, arg2 : valueType ): void { - select( valueType ){ - when int do writeln( arg1, " and ", arg2, " are ints" ); - when real do writeln( arg1, " and ", arg2, " are reals" ); - otherwise writeln( arg1, " and ", arg2, " are somethings!" ); - } -} - -genericProc( 1, 2 ); -genericProc( 1.2, 2.3 ); -genericProc( 1.0+2.0i, 3.0+4.0i ); - -// We can also enforce a form of polymorphism with the 'where' clause -// This allows the compiler to decide which function to use. -// Note: that means that all information needs to be known at compile-time. -// The param modifier on the arg is used to enforce this constraint. -proc whereProc( param N : int ): void - where ( N > 0 ) { - writeln( "N is greater than 0" ); +// elements in a data-structure are returned via a method or iterator. +proc refElement(array : [?D] ?T, idx) ref : T { + return array[idx]; } -proc whereProc( param N : int ): void - where ( N < 0 ) { - writeln( "N is less than 0" ); -} +var myChangingArray : [1..5] int = [1,2,3,4,5]; +writeln(myChangingArray); +ref refToElem = refElement(myChangingArray, 5); // store reference to element in ref variable +writeln(refToElem); +refToElem = -2; // modify reference which modifies actual value in array +writeln(refToElem); +writeln(myChangingArray); -whereProc( 10 ); -whereProc( -1 ); -// whereProc( 0 ) would result in a compiler error because there -// are no functions that satisfy the where clause's condition. -// We could have defined a whereProc without a where clause that would then have -// served as a catch all for all the other cases (of which there is only one). +// Operator Definitions -// Operator definitions are through procedures as well. +// Chapel allows for operators to be overloaded. // We can define the unary operators: // + - ! ~ // and the binary operators: // + - * / % ** == <= >= < > << >> & | ˆ by // += -= *= /= %= **= &= |= ˆ= <<= >>= <=> -// Boolean exclusive or operator -proc ^( left : bool, right : bool ): bool { - return (left || right) && !( left && right ); +// Boolean exclusive or operator. +proc ^(left : bool, right : bool): bool { + return (left || right) && !(left && right); } -writeln( true ^ true ); -writeln( false ^ true ); -writeln( true ^ false ); -writeln( false ^ false ); +writeln(true ^ true); +writeln(false ^ true); +writeln(true ^ false); +writeln(false ^ false); -// Define a * operator on any two types that returns a tuple of those types -proc *( left : ?ltype, right : ?rtype): ( ltype, rtype ){ - return (left, right ); +// Define a * operator on any two types that returns a tuple of those types. +proc *(left : ?ltype, right : ?rtype): (ltype, rtype) { + writeln("\tIn our '*' overload!"); + return (left, right); } -writeln( 1 * "a" ); // Uses our * operator -writeln( 1 * 2 ); // Uses the default * operator +writeln(1 * "a"); // Uses our * operator. +writeln(1 * 2); // Uses the default * operator. + +// Note: You could break everything if you get careless with your overloads. +// This here will break everything. Don't do it. /* -Note: You could break everything if you get careless with your overloads. -This here will break everything. Don't do it. -proc +( left: int, right: int ): int{ - return left - right; -} + proc +(left: int, right: int): int { + return left - right; + } */ -// Iterators are a sisters to the procedure, and almost -// everything about procedures also applies to iterators -// However, instead of returning a single value, -// iterators yield many values to a loop. -// This is useful when a complicated set or order of iterations is needed but -// allows the code defining the iterations to be separate from the loop body. -iter oddsThenEvens( N: int ): int { +// Iterators + +// Iterators are sisters to the procedure, and almost everything about +// procedures also applies to iterators. However, instead of returning a single +// value, iterators may yield multiple values to a loop. +// +// This is useful when a complicated set or order of iterations is needed, as +// it allows the code defining the iterations to be separate from the loop +// body. +iter oddsThenEvens(N: int): int { for i in 1..N by 2 do yield i; // yield values instead of returning. for i in 2..N by 2 do yield i; } -for i in oddsThenEvens( 10 ) do write( i, ", " ); -writeln( ); +for i in oddsThenEvens(10) do write(i, ", "); +writeln(); // Iterators can also yield conditionally, the result of which can be nothing -iter absolutelyNothing( N ): int { +iter absolutelyNothing(N): int { for i in 1..N { - if ( N < i ) { // Always false + if N < i { // Always false yield i; // Yield statement never happens } } } -for i in absolutelyNothing( 10 ){ - writeln( "Woa there! absolutelyNothing yielded ", i ); +for i in absolutelyNothing(10) { + writeln("Woa there! absolutelyNothing yielded ", i); } // We can zipper together two or more iterators (who have the same number -// of iterations) using zip() to create a single zipped iterator, where each +// of iterations) using zip() to create a single zipped iterator, where each // iteration of the zipped iterator yields a tuple of one value yielded // from each iterator. - // Ranges have implicit iterators -for (positive, negative) in zip( 1..5, -5..-1) do - writeln( (positive, negative) ); +for (positive, negative) in zip(1..5, -5..-1) do + writeln((positive, negative)); // Zipper iteration is quite important in the assignment of arrays, // slices of arrays, and array/loop expressions. var fromThatArray : [1..#5] int = [1,2,3,4,5]; var toThisArray : [100..#5] int; -// The operation +// Some zipper operations implement other operations. +// The first statement and the loop are equivalent. toThisArray = fromThatArray; -// is produced through -for (i,j) in zip( toThisArray.domain, fromThatArray.domain) { - toThisArray[ i ] = fromThatArray[ j ]; +for (i,j) in zip(toThisArray.domain, fromThatArray.domain) { + toThisArray[i] = fromThatArray[j]; } -toThisArray = [ j in -100..#5 ] j; -writeln( toThisArray ); -// is produced through -for (i, j) in zip( toThisArray.domain, -100..#5 ){ +// These two chunks are also equivalent. +toThisArray = [j in -100..#5] j; +writeln(toThisArray); + +for (i, j) in zip(toThisArray.domain, -100..#5) { toThisArray[i] = j; } -writeln( toThisArray ); +writeln(toThisArray); + +// This is very important in understanding why this statement exhibits a +// runtime error. + +/* + var iterArray : [1..10] int = [i in 1..10] if (i % 2 == 1) then i; +*/ -// This is all very important in understanding why the statement -// var iterArray : [1..10] int = [ i in 1..10 ] if ( i % 2 == 1 ) then j; -// exhibits a runtime error. // Even though the domain of the array and the loop-expression are // the same size, the body of the expression can be thought of as an iterator. // Because iterators can yield nothing, that iterator yields a different number // of things than the domain of the array or loop, which is not allowed. -// Classes are similar to those in C++ and Java. -// They currently lack privatization +// Classes + +// Classes are similar to those in C++ and Java, allocated on the heap. class MyClass { - // Member variables + +// Member variables var memberInt : int; var memberBool : bool = true; - // Classes have default constructors that don't need to be coded (see below) - // Our explicitly defined constructor - proc MyClass( val : real ){ - this.memberInt = ceil( val ): int; +// Explicitly defined initializer. +// We also get the compiler-generated initializer, with one argument per field. +// Note that soon there will be no compiler-generated initializer when we +// define any initializer(s) explicitly. + proc MyClass(val : real) { + this.memberInt = ceil(val): int; } - // Our explicitly defined destructor - proc ~MyClass( ){ - writeln( "MyClass Destructor called ", (this.memberInt, this.memberBool) ); +// Explicitly defined deinitializer. +// If we did not write one, we would get the compiler-generated deinitializer, +// which has an empty body. + proc deinit() { + writeln("MyClass deinitializer called ", (this.memberInt, this.memberBool)); } - // Class methods - proc setMemberInt( val: int ){ +// Class methods. + proc setMemberInt(val: int) { this.memberInt = val; } - proc setMemberBool( val: bool ){ + proc setMemberBool(val: bool) { this.memberBool = val; } - proc getMemberInt( ): int{ + proc getMemberInt(): int{ return this.memberInt; } - proc getMemberBool( ): bool { + proc getMemberBool(): bool { return this.memberBool; } - -} - -// Construct using default constructor, using default values -var myObject = new MyClass( 10 ); - myObject = new MyClass( memberInt = 10 ); // Equivalent -writeln( myObject.getMemberInt( ) ); -// ... using our values -var myDiffObject = new MyClass( -1, true ); - myDiffObject = new MyClass( memberInt = -1, - memberBool = true ); // Equivalent -writeln( myDiffObject ); - -// Construct using written constructor -var myOtherObject = new MyClass( 1.95 ); - myOtherObject = new MyClass( val = 1.95 ); // Equivalent -writeln( myOtherObject.getMemberInt( ) ); - -// We can define an operator on our class as well but -// the definition has to be outside the class definition -proc +( A : MyClass, B : MyClass) : MyClass { - return new MyClass( memberInt = A.getMemberInt( ) + B.getMemberInt( ), - memberBool = A.getMemberBool( ) || B.getMemberBool( ) ); +} // end MyClass + +// Call compiler-generated initializer, using default value for memberBool. +var myObject = new MyClass(10); + myObject = new MyClass(memberInt = 10); // Equivalent +writeln(myObject.getMemberInt()); + +// Same, but provide a memberBool value explicitly. +var myDiffObject = new MyClass(-1, true); + myDiffObject = new MyClass(memberInt = -1, + memberBool = true); // Equivalent +writeln(myDiffObject); + +// Call the initializer we wrote. +var myOtherObject = new MyClass(1.95); + myOtherObject = new MyClass(val = 1.95); // Equivalent +writeln(myOtherObject.getMemberInt()); + +// We can define an operator on our class as well, but +// the definition has to be outside the class definition. +proc +(A : MyClass, B : MyClass) : MyClass { + return new MyClass(memberInt = A.getMemberInt() + B.getMemberInt(), + memberBool = A.getMemberBool() || B.getMemberBool()); } var plusObject = myObject + myDiffObject; -writeln( plusObject ); +writeln(plusObject); -// Destruction +// Destruction. delete myObject; delete myDiffObject; delete myOtherObject; @@ -710,346 +774,362 @@ class MyChildClass : MyClass { var memberComplex: complex; } -// Generic Classes +// Here's an example of generic classes. class GenericClass { type classType; var classDomain: domain(1); var classArray: [classDomain] classType; - // Explicit constructor - proc GenericClass( type classType, elements : int ){ +// Explicit constructor. + proc GenericClass(type classType, elements : int) { this.classDomain = {1..#elements}; } - // Copy constructor - // Note: We still have to put the type as an argument, but we can - // default to the type of the other object using the query (?) operator - // Further, we can take advantage of this to allow our copy constructor - // to copy classes of different types and cast on the fly - proc GenericClass( other : GenericClass(?otherType), - type classType = otherType ) { +// Copy constructor. +// Note: We still have to put the type as an argument, but we can +// default to the type of the other object using the query (?) operator. +// Further, we can take advantage of this to allow our copy constructor +// to copy classes of different types and cast on the fly. + proc GenericClass(other : GenericClass(?otherType), + type classType = otherType) { this.classDomain = other.classDomain; // Copy and cast - for idx in this.classDomain do this[ idx ] = other[ idx ] : classType; + for idx in this.classDomain do this[idx] = other[idx] : classType; } - // Define bracket notation on a GenericClass - // object so it can behave like a normal array - // i.e. objVar[ i ] or objVar( i ) - proc this( i : int ) ref : classType { - return this.classArray[ i ]; +// Define bracket notation on a GenericClass +// object so it can behave like a normal array +// i.e. objVar[i] or objVar(i) + proc this(i : int) ref : classType { + return this.classArray[i]; } - // Define an implicit iterator for the class - // to yield values from the array to a loop - // i.e. for i in objVar do .... - iter these( ) ref : classType { +// Define an implicit iterator for the class +// to yield values from the array to a loop +// i.e. for i in objVar do ... + iter these() ref : classType { for i in this.classDomain do yield this[i]; } +} // end GenericClass -} - -var realList = new GenericClass( real, 10 ); // We can assign to the member array of the object using the bracket -// notation that we defined ( proc this( i: int ){ ... } ) +// notation that we defined. +var realList = new GenericClass(real, 10); for i in realList.classDomain do realList[i] = i + 1.0; + // We can iterate over the values in our list with the iterator -// we defined ( iter these( ){ ... } ) -for value in realList do write( value, ", " ); -writeln( ); +// we defined. +for value in realList do write(value, ", "); +writeln(); -// Make a copy of realList using the copy constructor -var copyList = new GenericClass( realList ); -for value in copyList do write( value, ", " ); -writeln( ); +// Make a copy of realList using the copy constructor. +var copyList = new GenericClass(realList); +for value in copyList do write(value, ", "); +writeln(); -// Make a copy of realList and change the type, also using the copy constructor -var copyNewTypeList = new GenericClass( realList, int ); -for value in copyNewTypeList do write( value, ", " ); -writeln( ); +// Make a copy of realList and change the type, also using the copy constructor. +var copyNewTypeList = new GenericClass(realList, int); +for value in copyNewTypeList do write(value, ", "); +writeln(); + + +// Modules // Modules are Chapel's way of managing name spaces. // The files containing these modules do not need to be named after the modules // (as in Java), but files implicitly name modules. -// In this case, this file implicitly names the 'learnchapel' module +// For example, this file implicitly names the learnChapelInYMinutes module module OurModule { - // We can use modules inside of other modules. - use Time; // Time is one of the standard modules. - // We'll use this procedure in the parallelism section. - proc countdown( seconds: int ){ +// We can use modules inside of other modules. +// Time is one of the standard modules. + use Time; + +// We'll use this procedure in the parallelism section. + proc countdown(seconds: int) { for i in 1..seconds by -1 { - writeln( i ); - sleep( 1 ); + writeln(i); + sleep(1); } } - // Submodules of OurModule - // It is possible to create arbitrarily deep module nests. +// It is possible to create arbitrarily deep module nests. +// i.e. submodules of OurModule module ChildModule { - proc foo(){ - writeln( "ChildModule.foo()"); + proc foo() { + writeln("ChildModule.foo()"); } } module SiblingModule { - proc foo(){ - writeln( "SiblingModule.foo()" ); + proc foo() { + writeln("SiblingModule.foo()"); } } } // end OurModule // Using OurModule also uses all the modules it uses. -// Since OurModule uses Time, we also use time. +// Since OurModule uses Time, we also use Time. use OurModule; -// At this point we have not used ChildModule or SiblingModule so their symbols -// (i.e. foo ) are not available to us. -// However, the module names are, and we can explicitly call foo() through them. -SiblingModule.foo(); // Calls SiblingModule.foo() - -// Super explicit naming. -OurModule.ChildModule.foo(); // Calls ChildModule.foo() +// At this point we have not used ChildModule or SiblingModule so +// their symbols (i.e. foo) are not available to us. However, the module +// names are available, and we can explicitly call foo() through them. +SiblingModule.foo(); +OurModule.ChildModule.foo(); +// Now we use ChildModule, enabling unqualified calls. use ChildModule; -foo(); // Less explicit call on ChildModule.foo() +foo(); + +// Parallelism + +// In other languages, parallelism is typically done with +// complicated libraries and strange class structure hierarchies. +// Chapel has it baked right into the language. -// We can declare a main procedure -// Note: all the code above main still gets executed. -proc main(){ +// We can declare a main procedure, but all the code above main still gets +// executed. +proc main() { + writeln("PARALLELISM START"); - // Parallelism - // In other languages, parallelism is typically done with - // complicated libraries and strange class structure hierarchies. - // Chapel has it baked right into the language. +// A begin statement will spin the body of that statement off +// into one new task. +// A sync statement will ensure that the progress of the main +// task will not progress until the children have synced back up. - // A begin statement will spin the body of that statement off - // into one new task. - // A sync statement will ensure that the progress of the main - // task will not progress until the children have synced back up. sync { begin { // Start of new task's body var a = 0; for i in 1..1000 do a += 1; - writeln( "Done: ", a); + writeln("Done: ", a); } // End of new tasks body - writeln( "spun off a task!"); + writeln("spun off a task!"); } - writeln( "Back together" ); + writeln("Back together"); - proc printFibb( n: int ){ - writeln( "fibonacci(",n,") = ", fibonacci( n ) ); + proc printFibb(n: int) { + writeln("fibonacci(",n,") = ", fibonacci(n)); } - // A cobegin statement will spin each statement of the body into one new task +// A cobegin statement will spin each statement of the body into one new +// task. Notice here that the prints from each statement may happen in any +// order. cobegin { - printFibb( 20 ); // new task - printFibb( 10 ); // new task - printFibb( 5 ); // new task + printFibb(20); // new task + printFibb(10); // new task + printFibb(5); // new task { // This is a nested statement body and thus is a single statement - // to the parent statement and is executed by a single task - writeln( "this gets" ); - writeln( "executed as" ); - writeln( "a whole" ); + // to the parent statement, executed by a single task. + writeln("this gets"); + writeln("executed as"); + writeln("a whole"); } } - // Notice here that the prints from each statement may happen in any order. - // Coforall loop will create a new task for EACH iteration +// A coforall loop will create a new task for EACH iteration. +// Again we see that prints happen in any order. +// NOTE: coforall should be used only for creating tasks! +// Using it to iterating over a structure is very a bad idea! var num_tasks = 10; // Number of tasks we want coforall taskID in 1..#num_tasks { - writeln( "Hello from task# ", taskID ); + writeln("Hello from task# ", taskID); } - // Again we see that prints happen in any order. - // NOTE! coforall should be used only for creating tasks! - // Using it to iterating over a structure is very a bad idea! - // forall loops are another parallel loop, but only create a smaller number - // of tasks, specifically --dataParTasksPerLocale=number of task +// forall loops are another parallel loop, but only create a smaller number +// of tasks, specifically --dataParTasksPerLocale= number of tasks. forall i in 1..100 { - write( i, ", "); + write(i, ", "); } - writeln( ); - // Here we see that there are sections that are in order, followed by - // a section that would not follow ( e.g. 1, 2, 3, 7, 8, 9, 4, 5, 6, ). - // This is because each task is taking on a chunk of the range 1..10 - // (1..3, 4..6, or 7..9) doing that chunk serially, but each task happens - // in parallel. - // Your results may depend on your machine and configuration - - // For both the forall and coforall loops, the execution of the - // parent task will not continue until all the children sync up. - - // forall loops are particularly useful for parallel iteration over arrays. - // Lets run an experiment to see how much faster a parallel loop is + writeln(); + +// Here we see that there are sections that are in order, followed by +// a section that would not follow (e.g. 1, 2, 3, 7, 8, 9, 4, 5, 6,). +// This is because each task is taking on a chunk of the range 1..10 +// (1..3, 4..6, or 7..9) doing that chunk serially, but each task happens +// in parallel. Your results may depend on your machine and configuration + +// For both the forall and coforall loops, the execution of the +// parent task will not continue until all the children sync up. + +// forall loops are particularly useful for parallel iteration over arrays. +// Lets run an experiment to see how much faster a parallel loop is use Time; // Import the Time module to use Timer objects var timer: Timer; var myBigArray: [{1..4000,1..4000}] real; // Large array we will write into - // Serial Experiment - timer.start( ); // Start timer +// Serial Experiment: + timer.start(); // Start timer for (x,y) in myBigArray.domain { // Serial iteration myBigArray[x,y] = (x:real) / (y:real); } - timer.stop( ); // Stop timer - writeln( "Serial: ", timer.elapsed( ) ); // Print elapsed time - timer.clear( ); // Clear timer for parallel loop + timer.stop(); // Stop timer + writeln("Serial: ", timer.elapsed()); // Print elapsed time + timer.clear(); // Clear timer for parallel loop - // Parallel Experiment - timer.start( ); // start timer +// Parallel Experiment: + timer.start(); // start timer forall (x,y) in myBigArray.domain { // Parallel iteration myBigArray[x,y] = (x:real) / (y:real); } - timer.stop( ); // Stop timer - writeln( "Parallel: ", timer.elapsed( ) ); // Print elapsed time - timer.clear( ); - // You may have noticed that (depending on how many cores you have) - // that the parallel loop went faster than the serial loop - - // The bracket style loop-expression described - // much earlier implicitly uses a forall loop. - [ val in myBigArray ] val = 1 / val; // Parallel operation - - // Atomic variables, common to many languages, are ones whose operations - // occur uninterrupted. Multiple threads can both modify atomic variables - // and can know that their values are safe. - // Chapel atomic variables can be of type bool, int, uint, and real. + timer.stop(); // Stop timer + writeln("Parallel: ", timer.elapsed()); // Print elapsed time + timer.clear(); + +// You may have noticed that (depending on how many cores you have) +// the parallel loop went faster than the serial loop. + +// The bracket style loop-expression described +// much earlier implicitly uses a forall loop. + [val in myBigArray] val = 1 / val; // Parallel operation + +// Atomic variables, common to many languages, are ones whose operations +// occur uninterrupted. Multiple threads can therefore modify atomic +// variables and can know that their values are safe. +// Chapel atomic variables can be of type bool, int, +// uint, and real. var uranium: atomic int; - uranium.write( 238 ); // atomically write a variable - writeln( uranium.read() ); // atomically read a variable + uranium.write(238); // atomically write a variable + writeln(uranium.read()); // atomically read a variable - // operations are described as functions, you could define your own operators. - uranium.sub( 3 ); // atomically subtract a variable - writeln( uranium.read() ); +// Atomic operations are described as functions, so you can define your own. + uranium.sub(3); // atomically subtract a variable + writeln(uranium.read()); var replaceWith = 239; - var was = uranium.exchange( replaceWith ); - writeln( "uranium was ", was, " but is now ", replaceWith ); + var was = uranium.exchange(replaceWith); + writeln("uranium was ", was, " but is now ", replaceWith); var isEqualTo = 235; - if ( uranium.compareExchange( isEqualTo, replaceWith ) ) { - writeln( "uranium was equal to ", isEqualTo, - " so replaced value with ", replaceWith ); + if uranium.compareExchange(isEqualTo, replaceWith) { + writeln("uranium was equal to ", isEqualTo, + " so replaced value with ", replaceWith); } else { - writeln( "uranium was not equal to ", isEqualTo, - " so value stays the same... whatever it was" ); + writeln("uranium was not equal to ", isEqualTo, + " so value stays the same... whatever it was"); } sync { begin { // Reader task - writeln( "Reader: waiting for uranium to be ", isEqualTo ); - uranium.waitFor( isEqualTo ); - writeln( "Reader: uranium was set (by someone) to ", isEqualTo ); + writeln("Reader: waiting for uranium to be ", isEqualTo); + uranium.waitFor(isEqualTo); + writeln("Reader: uranium was set (by someone) to ", isEqualTo); } begin { // Writer task - writeln( "Writer: will set uranium to the value ", isEqualTo, " in..." ); - countdown( 3 ); - uranium.write( isEqualTo ); + writeln("Writer: will set uranium to the value ", isEqualTo, " in..."); + countdown(3); + uranium.write(isEqualTo); } } - // sync vars have two states: empty and full. - // If you read an empty variable or write a full variable, you are waited - // until the variable is full or empty again +// sync variables have two states: empty and full. +// If you read an empty variable or write a full variable, you are waited +// until the variable is full or empty again. var someSyncVar$: sync int; // varName$ is a convention not a law. sync { begin { // Reader task - writeln( "Reader: waiting to read." ); + writeln("Reader: waiting to read."); var read_sync = someSyncVar$; - writeln( "Reader: value is ", read_sync ); + writeln("Reader: value is ", read_sync); } begin { // Writer task - writeln( "Writer: will write in..." ); - countdown( 3 ); + writeln("Writer: will write in..."); + countdown(3); someSyncVar$ = 123; } } - // single vars can only be written once. A read on an unwritten single results - // in a wait, but when the variable has a value it can be read indefinitely +// single vars can only be written once. A read on an unwritten single +// results in a wait, but when the variable has a value it can be read +// indefinitely. var someSingleVar$: single int; // varName$ is a convention not a law. sync { begin { // Reader task - writeln( "Reader: waiting to read." ); + writeln("Reader: waiting to read."); for i in 1..5 { var read_single = someSingleVar$; - writeln( "Reader: iteration ", i,", and the value is ", read_single ); + writeln("Reader: iteration ", i,", and the value is ", read_single); } } begin { // Writer task - writeln( "Writer: will write in..." ); - countdown( 3 ); + writeln("Writer: will write in..."); + countdown(3); someSingleVar$ = 5; // first and only write ever. } } - // Heres an example of using atomics and a synch variable to create a - // count-down mutex (also known as a multiplexer) +// Heres an example using atomics and a sync variable to create a +// count-down mutex (also known as a multiplexer). var count: atomic int; // our counter var lock$: sync bool; // the mutex lock - count.write( 2 ); // Only let two tasks in at a time. - lock$.writeXF( true ); // Set lock$ to full (unlocked) + count.write(2); // Only let two tasks in at a time. + lock$.writeXF(true); // Set lock$ to full (unlocked) // Note: The value doesnt actually matter, just the state // (full:unlocked / empty:locked) // Also, writeXF() fills (F) the sync var regardless of its state (X) coforall task in 1..#5 { // Generate tasks // Create a barrier - do{ + do { lock$; // Read lock$ (wait) - }while ( count.read() < 1 ); // Keep waiting until a spot opens up + } while (count.read() < 1); // Keep waiting until a spot opens up count.sub(1); // decrement the counter - lock$.writeXF( true ); // Set lock$ to full (signal) + lock$.writeXF(true); // Set lock$ to full (signal) // Actual 'work' - writeln( "Task #", task, " doing work." ); - sleep( 2 ); + writeln("Task #", task, " doing work."); + sleep(2); - count.add( 1 ); // Increment the counter - lock$.writeXF( true ); // Set lock$ to full (signal) + count.add(1); // Increment the counter + lock$.writeXF(true); // Set lock$ to full (signal) } - // we can define the operations + * & | ^ && || min max minloc maxloc - // over an entire array using scans and reductions - // Reductions apply the operation over the entire array and - // result in a single value +// We can define the operations + * & | ^ && || min max minloc maxloc +// over an entire array using scans and reductions. +// Reductions apply the operation over the entire array and +// result in a scalar value. var listOfValues: [1..10] int = [15,57,354,36,45,15,456,8,678,2]; var sumOfValues = + reduce listOfValues; var maxValue = max reduce listOfValues; // 'max' give just max value - // 'maxloc' gives max value and index of the max value - // Note: We have to zip the array and domain together with the zip iterator +// maxloc gives max value and index of the max value. +// Note: We have to zip the array and domain together with the zip iterator. var (theMaxValue, idxOfMax) = maxloc reduce zip(listOfValues, listOfValues.domain); - writeln( (sumOfValues, maxValue, idxOfMax, listOfValues[ idxOfMax ] ) ); + writeln((sumOfValues, maxValue, idxOfMax, listOfValues[idxOfMax])); - // Scans apply the operation incrementally and return an array of the - // value of the operation at that index as it progressed through the - // array from array.domain.low to array.domain.high +// Scans apply the operation incrementally and return an array with the +// values of the operation at that index as it progressed through the +// array from array.domain.low to array.domain.high. var runningSumOfValues = + scan listOfValues; var maxScan = max scan listOfValues; - writeln( runningSumOfValues ); - writeln( maxScan ); + writeln(runningSumOfValues); + writeln(maxScan); } // end main() ``` Who is this tutorial for? ------------------------- -This tutorial is for people who want to learn the ropes of chapel without having to hear about what fiber mixture the ropes are, or how they were braided, or how the braid configurations differ between one another. -It won't teach you how to develop amazingly performant code, and it's not exhaustive. -Refer to the [language specification](http://chapel.cray.com/language.html) and the [module documentation](http://chapel.cray.com/docs/latest/) for more details. +This tutorial is for people who want to learn the ropes of chapel without +having to hear about what fiber mixture the ropes are, or how they were +braided, or how the braid configurations differ between one another. It won't +teach you how to develop amazingly performant code, and it's not exhaustive. +Refer to the [language specification](http://chapel.cray.com/language.html) and +the [module documentation](http://chapel.cray.com/docs/latest/) for more +details. -Occasionally check back here and on the [Chapel site](http://chapel.cray.com) to see if more topics have been added or more tutorials created. +Occasionally check back here and on the [Chapel site](http://chapel.cray.com) +to see if more topics have been added or more tutorials created. ### What this tutorial is lacking: @@ -1061,12 +1141,14 @@ Occasionally check back here and on the [Chapel site](http://chapel.cray.com) to Your input, questions, and discoveries are important to the developers! ----------------------------------------------------------------------- -The Chapel language is still in-development (version 1.12.0), so there are occasional hiccups with performance and language features. -The more information you give the Chapel development team about issues you encounter or features you would like to see, the better the language becomes. -Feel free to email the team and other developers through the [sourceforge email lists](https://sourceforge.net/p/chapel/mailman). +The Chapel language is still in-development (version 1.15.0), so there are +occasional hiccups with performance and language features. The more information +you give the Chapel development team about issues you encounter or features you +would like to see, the better the language becomes. Feel free to email the team +and other developers through the [sourceforge email lists](https://sourceforge.net/p/chapel/mailman). -If you're really interested in the development of the compiler or contributing to the project, -[check out the master GitHub repository](https://github.com/chapel-lang/chapel). +If you're really interested in the development of the compiler or contributing +to the project, [check out the master GitHub repository](https://github.com/chapel-lang/chapel). It is under the [Apache 2.0 License](http://www.apache.org/licenses/LICENSE-2.0). Installing the Compiler @@ -1076,12 +1158,15 @@ Chapel can be built and installed on your average 'nix machine (and cygwin). [Download the latest release version](https://github.com/chapel-lang/chapel/releases/) and it's as easy as - 1. `tar -xvf chapel-1.12.0.tar.gz` - 2. `cd chapel-1.12.0` - 3. `make` - 4. `source util/setchplenv.bash # or .sh or .csh or .fish` + 1. `tar -xvf chapel-1.15.0.tar.gz` + 2. `cd chapel-1.15.0` + 3. `source util/setchplenv.bash # or .sh or .csh or .fish` + 4. `make` + 5. `make check # optional` -You will need to `source util/setchplenv.EXT` from within the Chapel directory (`$CHPL_HOME`) every time your terminal starts so it's suggested that you drop that command in a script that will get executed on startup (like .bashrc). +You will need to `source util/setchplenv.EXT` from within the Chapel directory +(`$CHPL_HOME`) every time your terminal starts so it's suggested that you drop +that command in a script that will get executed on startup (like .bashrc). Chapel is easily installed with Brew for OS X @@ -1097,7 +1182,10 @@ Builds like other compilers: Notable arguments: - * `--fast`: enables a number of optimizations and disables array bounds checks. Should only enable when application is stable. - * `--set <Symbol Name>=<Value>`: set config param `<Symbol Name>` to `<Value>` at compile-time. - * `--main-module <Module Name>`: use the main() procedure found in the module `<Module Name>` as the executable's main. + * `--fast`: enables a number of optimizations and disables array bounds + checks. Should only enable when application is stable. + * `--set <Symbol Name>=<Value>`: set config param `<Symbol Name>` to `<Value>` + at compile-time. + * `--main-module <Module Name>`: use the main() procedure found in the module + `<Module Name>` as the executable's main. * `--module-dir <Directory>`: includes `<Directory>` in the module search path. |