It's not clear how hypothetical operator should behave in case of multi-D slices. Your "reshape" solution simply fills new container with existing data regardless of row/column/plane boundaries, just like pouring liquid from one vessel to another of different shape, under normal gravity, and it's only exact volume that matters. Should 2-D matrix be perhaps transposed? Anyway, existing facilities can solve these tasks without repeating a slice expression twice -- if that's what you want to avoid.
E.g., for "liquid data to fill new vessel", both RHS and LHS piddles can be flattened, and since the latter is virtual, changes will flow to original multi-D piddle:
pdl> p$p = sequence 2,5
[
[0 1]
[2 3]
[4 5]
[6 7]
[8 9]
]
pdl> p$t3 = $t2 = ($t1 = zeroes 4,3) .= -1
[
[-1 -1 -1 -1]
[-1 -1 -1 -1]
[-1 -1 -1 -1]
]
pdl> $t1(0:2,1:2)->(;_) .= $p(0:1,1:3)->(;_); p$t1
[
[-1 -1 -1 -1]
[ 2 3 4 -1]
[ 5 6 7 -1]
]
pdl> $t2(0:2,1:2)->flat .= $p(0:1,1:3)->flat; p$t2 # the same
[
[-1 -1 -1 -1]
[ 2 3 4 -1]
[ 5 6 7 -1]
]
pdl> $t3(0:2,1:2) .= $p(0:1,1:3)->transpose; p$t3
[
[-1 -1 -1 -1]
[ 2 4 6 -1]
[ 3 5 7 -1]
]
pdl>
