If computations are not instantaneous then how else would it work? I thought his thesis was rather the same as this blog post- that programs should be composabl

If computations are not instantaneous then how else would it work? I thought his thesis was rather the same as this blog post- that programs should be composable mathematical expressions rather than bit-twiddling word-shoveling statements- but it's been forever since I read that and I probably didn't appreciate it at the time.