About the last paragraph, R and Pandas both have that issue. (Although I'm not sure if it's a bottleneck in typical code, since there are other problems too.)

About the last paragraph, R and Pandas both have that issue. (Although I'm not sure if it's a bottleneck in typical code, since there are other problems too.) But Julia and the newer Weld compiler apparently have loop fusion: https://julialang.org/blog/2017/01/moredots/ https://julialang.org/blog/2017/01/moredots/ https://dawn.cs.stanford.edu/2018/07/30/weldopt/ https://dawn.cs.stanford.edu/2018/07/30/weldopt/