digitalmars.D.learn - Need help with calling a list of functions
- Luigi (18/18) Nov 03 2018 I need to call a function that can create a function from an
- Paul Backus (8/26) Nov 03 2018 Use recursion:
- =?UTF-8?Q?Ali_=c3=87ehreli?= (22/44) Nov 03 2018 Here is one that uses a loop:
- Sebastiaan Koppe (2/5) Nov 04 2018 That sounds a lot like std.functional.compose
I need to call a function that can create a function from an array of functions and calls them in reverse order. I am learning D any help would be import std.stdio; import std.algorithm; import std.array : array; import std.range; auto comp(T)(T function(T) [] list) pure { auto backwards = retro(funs); return <<HEre is where I think I need some help in calling the list of functions with a delegate and fold or reduce>>; } void main() { auto fun = comp([(real x)=>a/3.0,(real x)=>x*x,(real x)=>x+1.0]); writeln(fun(2.0)); // should print 3 }
Nov 03 2018
On Sunday, 4 November 2018 at 01:17:01 UTC, Luigi wrote:I need to call a function that can create a function from an array of functions and calls them in reverse order. I am learning D any help would be import std.stdio; import std.algorithm; import std.array : array; import std.range; auto comp(T)(T function(T) [] list) pure { auto backwards = retro(funs); return <<HEre is where I think I need some help in calling the list of functions with a delegate and fold or reduce>>; } void main() { auto fun = comp([(real x)=>a/3.0,(real x)=>x*x,(real x)=>x+1.0]); writeln(fun(2.0)); // should print 3 }Use recursion: T delegate(T) comp(T)(T function(T) [] list) pure { if (list.length == 1) return (T arg) => list[0](arg); else return (T arg) => list[0](comp(list[1 .. $])(arg)); }
Nov 03 2018
On 11/03/2018 06:17 PM, Luigi wrote:I need to call a function that can create a function from an array of functions and calls them in reverse order. I am learning D any help would be import std.stdio; import std.algorithm; import std.array : array; import std.range; auto comp(T)(T function(T) [] list) pure { auto backwards = retro(funs); return <<HEre is where I think I need some help in calling the list of functions with a delegate and fold or reduce>>; } void main() { auto fun = comp([(real x)=>a/3.0,(real x)=>x*x,(real x)=>x+1.0]); writeln(fun(2.0)); // should print 3 }Here is one that uses a loop: import std.stdio; import std.range : front; import std.traits : ReturnType; auto comp(Funcs...)(Funcs funcs) pure { alias R = ReturnType!(typeof([funcs].front)); auto impl(R x) { foreach_reverse (func; funcs) { x = func(x); } return x; } return (double x) => impl(x); } void main() { auto fun = comp((real x)=>x/3.0,(real x)=>x*x,(real x)=>x+1.0); assert(fun(2.0) == 3); } I used a variadic template parameter instead of an array parameter. Ali
Nov 03 2018
On Sunday, 4 November 2018 at 01:17:01 UTC, Luigi wrote:I need to call a function that can create a function from an array of functions and calls them in reverse order. I am learning D any help would beThat sounds a lot like std.functional.compose
Nov 04 2018