Re: Writing a simple Core evaluator, having trouble with name lookups

I'm aware that unique names are unique in a GHC invocation. But my statements sill holds. On Fri, Nov 30, 2018 at 7:20 PM Ben Gamari wrote:

Csaba Hruska writes:

...

Hi Ben,

I thought that it is possible to rely on unique values *in case of non exported Ids* because they are local to a specific module and can not appear in expressions in other modules because they are not exported. Do I miss something?

Uniques should be treated as being non-reproducible across compiler sessions.

To make this more concrete: if GHC compiles the same module twice it will not necessarily assign the same uniques to the module's Names. Uniques are derived from local UniqSupplies conjured up at a variety of points in the compilation pipeline (search from mkSplitUniqSupply).

These supplies are themselves derived from an impure global counter (see compiler/cbits/genSym.c). The state of this counter (and consequently the uniques derived from it) should be treated as being entirely unpredictable.

Cheers,

- Ben