Behavior of joining mapresults

[Christian Köstlin]

On 20.12.17 17:30, Christian Köstlin wrote:
> thats an idea, thank a lot, will give it a try ...
#!/usr/bin/env rdmd -unittest
unittest {
    import std.stdio;
    import std.range;
    import std.algorithm;
    import std.string;
    import std.functional;

    auto parse(int i) {
        writeln("parsing %s".format(i));
        return [1, 2, 3];
    }

    writeln(iota(1, 5).map!(memoize!parse));
    writeln("-------------------------------");
    writeln((iota(1, 5).map!(memoize!parse)).joiner);
}

void main() {}

works, but i fear for the data that is stored in the memoization. at the
moment its not a big issue, as all the data fits comfortable into ram,
but for bigger data another approach is needed (probably even my current
json parsing must be exchanged).

I still wonder, if the joiner calls front more often than necessary. For
sure its valid to call front as many times as one sees fit, but with a
lazy map in between, it might not be the best solution.