Behavior of joining mapresults

[Stefan Koch]

On Wednesday, 20 December 2017 at 15:28:00 UTC, Christian Köstlin 
wrote:
> When working with json data files, that we're a little bigger 
> than
> convenient I stumbled upon a strange behavior with joining of 
> mapresults
> (I understand that this is more or less flatmap).
> I mapped inputfiles, to JSONValues, from which I took out some 
> arrays,
> whose content I wanted to join.
> Although the joiner is at the end of the functional pipe, it 
> led to
> calling of the parsing code twice.
> I tried to reduce the problem:
>
> [...]

you need to memorize I guess, map is lazy.