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/***********************************************************************
* Chapel implementation of "99 bottles of beer"
*
* by Brad Chamberlain and Steve Deitz
* 07/13/2006 in Knoxville airport while waiting for flight home from
* HPLS workshop
* compiles and runs with chpl compiler version 1.7.0
* for more information, contact: chapel_info@cray.com
*
*
* Notes:
* o as in all good parallel computations, boundary conditions
* constitute the vast bulk of complexity in this code (invite Brad to
* tell you about his zany boundary condition simplification scheme)
* o uses type inference for variables, arguments
* o relies on integer->string coercions
* o uses named argument passing (for documentation purposes only)
***********************************************************************/
// allow executable command-line specification of number of bottles
// (e.g., ./a.out -snumBottles=999999)
config const numBottles = 99;
const numVerses = numBottles+1;
// a domain to describe the space of lyrics
var LyricsSpace: domain(1) = {1..numVerses};
// array of lyrics
var Lyrics: [LyricsSpace] string;
// parallel computation of lyrics array
[verse in LyricsSpace] Lyrics(verse) = computeLyric(verse);
// as in any good parallel language, I/O to stdout is serialized.
// (Note that I/O to a file could be parallelized using a parallel
// prefix computation on the verse strings' lengths with file seeking)
writeln(Lyrics);
// HELPER FUNCTIONS:
proc computeLyric(verseNum) {
var bottleNum = numBottles - (verseNum - 1);
var nextBottle = (bottleNum + numVerses - 1)%numVerses;
return "\n" // disguise space used to separate elements in array I/O
+ describeBottles(bottleNum, startOfVerse=true) + " on the wall, "
+ describeBottles(bottleNum) + ".\n"
+ computeAction(bottleNum)
+ describeBottles(nextBottle) + " on the wall.\n";
}
proc describeBottles(bottleNum, startOfVerse:bool = false) {
// NOTE: bool should not be necessary here (^^^^); working around bug
var bottleDescription = if (bottleNum) then bottleNum:string
else (if startOfVerse then "N"
else "n")
+ "o more";
return bottleDescription
+ " bottle" + (if (bottleNum == 1) then "" else "s")
+ " of beer";
}
proc computeAction(bottleNum) {
return if (bottleNum == 0) then "Go to the store and buy some more, "
else "Take one down and pass it around, ";
}
// Modules...
module M1 {
var x = 10;
}
module M2 {
use M1;
proc main() {
writeln("M2 -> M1 -> x " + x);
}
}
// Classes, records, unions...
const PI: real = 3.14159;
record Point {
var x, y: real;
}
var p: Point;
writeln("Distance from origin: " + sqrt(p.x ** 2 + p.y ** 2));
p = new Point(1.0, 2.0);
writeln("Distance from origin: " + sqrt(p.x ** 2 + p.y ** 2));
class Circle {
var p: Point;
var r: real;
}
var c = new Circle(r=2.0);
proc Circle.area()
return PI * r ** 2;
writeln("Area of circle: " + c.area());
class Oval: Circle {
var r2: real;
}
proc Oval.area()
return PI * r * r2;
delete c;
c = nil;
c = new Oval(r=1.0, r2=2.0);
writeln("Area of oval: " + c.area());
union U {
var i: int;
var r: real;
}
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