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Use Lambdas and UFCS in std.algorithm examples.

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Better represent Lambda syntax and UFCS in the map/filter/reduce examples in std.algorithm.
This commit is contained in:
cjoan 2013-03-07 21:55:36 -05:00
parent 29e043d461
commit c45e75a97a
1 changed files with 26 additions and 7 deletions
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33
std/algorithm.d
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@ -348,7 +348,7 @@ Example:
----
int[] arr1 = [ 1, 2, 3, 4 ];
int[] arr2 = [ 5, 6 ];
auto squares = map!("a * a")(chain(arr1, arr2));
auto squares = map!(a => a * a)(chain(arr1, arr2));
assert(equal(squares, [ 1, 4, 9, 16, 25, 36 ]));
----
@ -617,19 +617,27 @@ Example:
----
int[] arr = [ 1, 2, 3, 4, 5 ];
// Sum all elements
auto sum = reduce!("a + b")(0, arr);
auto sum = reduce!((a,b) => a + b)(0, arr);
assert(sum == 15);
// Sum again, using a string predicate with "a" and "b"
sum = reduce!"a + b"(0, arr);
assert(sum == 15);
// Compute the maximum of all elements
auto largest = reduce!(max)(arr);
assert(largest == 5);
// Max again, but with Uniform Function Call Syntax (UFCS)
largest = arr.reduce!(max);
assert(largest == 5);
// Compute the number of odd elements
auto odds = reduce!("a + (b & 1)")(0, arr);
auto odds = reduce!((a,b) => a + (b & 1))(0, arr);
assert(odds == 3);
// Compute the sum of squares
auto ssquares = reduce!("a + b * b")(0, arr);
auto ssquares = reduce!((a,b) => a + b * b)(0, arr);
assert(ssquares == 55);
// Chain multiple ranges into seed
@ -642,6 +650,10 @@ assert(r == 107);
double[] c = [ 2.5, 3.0 ];
auto r1 = reduce!("a + b")(chain(a, b, c));
assert(r1 == 112.5);
// To minimize nesting of parentheses, Uniform Function Call Syntax can be used
auto r2 = chain(a, b, c).reduce!("a + b");
assert(r2 == 112.5);
----
$(DDOC_SECTION_H Multiple functions:) Sometimes it is very useful to
@ -1255,17 +1267,24 @@ which $(D predicate(x)) is $(D true).
Example:
----
int[] arr = [ 1, 2, 3, 4, 5 ];
// Sum all elements
auto small = filter!("a < 3")(arr);
auto small = filter!(a => a < 3)(arr);
assert(equal(small, [ 1, 2 ]));
// Sum again, but with Uniform Function Call Syntax (UFCS)
auto sum = arr.filter!(a => a < 3);
assert(equal(sum, [ 1, 2 ]));
// In combination with chain() to span multiple ranges
int[] a = [ 3, -2, 400 ];
int[] b = [ 100, -101, 102 ];
auto r = filter!("a > 0")(chain(a, b));
auto r = chain(a, b).filter!(a => a > 0);
assert(equal(r, [ 3, 400, 100, 102 ]));
// Mixing convertible types is fair game, too
double[] c = [ 2.5, 3.0 ];
auto r1 = filter!("cast(int) a != a")(chain(c, a, b));
auto r1 = chain(c, a, b).filter!(a => cast(int) a != a);
assert(equal(r1, [ 2.5 ]));
----
*/