tvl-depot/users/sterni/nix/list/default.nix

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{ ... }:
{
/* For a list of length n that consists of lists of length m,
return a list of length m containing lists of length n
so that
builtins.elemAt (builtins.elemAt orig a) b
== builtins.elemAt (builtins.elemAt transposed b) a
Essentially, if you think of the nested list as an array with two
dimensions, the two index axes are swapped.
The length of the inner lists m is determined based on the first element
and assumed to be used for all other lists. Malformed input data may
cause the function to crash or lose data.
Type: <n>[ <m>[ ] ] -> <m>[ <n>[ ] ]
*/
transpose = list:
let
innerLength = builtins.length (builtins.head list);
outerLength = builtins.length list;
in
builtins.genList
(inner: builtins.genList
(outer: builtins.elemAt (builtins.elemAt list outer) inner)
outerLength)
innerLength;
}