import std.meta: AliasSeq;

​

template sMap(alias F, T...) {

    static if (T.length == 0) {

        alias sMap = AliasSeq!();

    } else static if (T.length == 1) {

        alias sMap = AliasSeq!(F!(T[0]));

    } else static if (T.length == 2) {

        alias sMap = AliasSeq!(F!(T[0]), F!(T[1]));

    } else static if (T.length == 3) {

        alias sMap = AliasSeq!(F!(T[0]), F!(T[1]), F!(T[2]));

    } else static if (T.length == 4) {

        alias sMap = AliasSeq!(F!(T[0]), F!(T[1]), F!(T[2]), F!(T[3]));

    } else {

        mixin(

            "alias sMap = AliasSeq!(",

            (){

                string argsList = "";

                static foreach(i, _; T) {

                    argsList ~= "F!(T[" ~ i.stringof ~ "]), ";

                }

                return argsList;

            }(),

            ");");

    }

}

​

void main() {

    import std.traits: Unqual;

    pragma(msg, sMap!(Unqual, immutable int));

}