On Wednesday, 13 August 2014 at 14:45:43 UTC, Jonathan M Davis
via Digitalmars-d-learn wrote:
They're called find and until. You just have to give them the
opposite
predicate that you'd give a function called dropIf or takeIf.
Ok, thx.
As an exercise I tried
auto dropWhile(R, E)(R range, E element) if (isInputRange!R &&
is(ElementType!R ==
E))
{
import std.algorithm: find;
return range.find(a => a != element);
}
unittest { dln([1, 2, 3].dropWhile(1)); }
but it errors as
algorithm_ex.d(1452,22): Error: template std.algorithm.find
cannot deduce function from argument types !()(int[], void),
candidates are:
/home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/algorithm.d(4261,12):
std.algorithm.find(alias pred = "a == b", InputRange,
Element)(InputRange haystack, Element needle) if
(isInputRange!InputRange &&
is(typeof(binaryFun!pred(haystack.front, needle)) : bool))
/home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/algorithm.d(4541,4):
std.algorithm.find(alias pred = "a == b", R1, R2)(R1
haystack, R2 needle) if (isForwardRange!R1 && isForwardRange!R2
&& is(typeof(binaryFun!pred(haystack.front, needle.front)) :
bool) && !isRandomAccessRange!R1)
/home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/algorithm.d(4589,4):
std.algorithm.find(alias pred = "a == b", R1, R2)(R1
haystack, R2 needle) if (isRandomAccessRange!R1 &&
isBidirectionalRange!R2 &&
is(typeof(binaryFun!pred(haystack.front, needle.front)) : bool))
/home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/algorithm.d(4661,4):
std.algorithm.find(alias pred = "a == b", R1, R2)(R1
haystack, R2 needle) if (isRandomAccessRange!R1 &&
isForwardRange!R2 && !isBidirectionalRange!R2 &&
is(typeof(binaryFun!pred(haystack.front, needle.front)) : bool))
/home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/algorithm.d(4887,23):
std.algorithm.find(alias pred = "a == b", Range,
Ranges...)(Range haystack, Ranges needles) if (Ranges.length > 1
&& is(typeof(startsWith!pred(haystack, needles))))
algorithm_ex.d(1452,22): ... (2 more, -v to show) ...
algorithm_ex.d(1456,35): Error: template instance
algorithm_ex.dropWhile!(int[], int) error instantiating
/home/per/Work/justd/msgpack.d(4614,25): Warning: calling
msgpack.pack!(false, string).pack without side effects discards
return value of type ubyte[], prepend a cast(void) if intentional
/home/per/Work/justd/msgpack.d(4614,25): Warning: calling
msgpack.pack!(false, string).pack without side effects discards
return value of type ubyte[], prepend a cast(void) if intentional
What have I done wrong?
