3 ms·

Lua uses a concept called "upvalues" to refer to variables from enclosing scopes. The main observation here seems to be that you can statically determine a uni

Lua uses a concept called "upvalues" to refer to variables from enclosing scopes. The main observation here seems to be that you can statically determine a unique index for all local variables in any enclosing scope. I'm not sure exactly how the details work in cases where there are sibling scopes, but anyway it seems like a useful concept and i am surprised the concept/terminology is not more common.

ScottBurson 11y ago
This technique is very old -- it goes back at least to Pascal, IIRC, and probably to Algol 60. It certainly was used in Scheme implementations in the late 1970s. I haven't heard the term "upvalue" before, though.
- haberman 11y ago
  That's sort of my point. There seems to be some established knowledge about how you can address "upvalues" within closures but very little shared terminology or literature about it.
- rjeli 11y ago
  Tcl uses uplevel to evaluate a block of code in the current context.