I had my own qualms with the language itself too. My team had very complex Borg configs, so complex they took more than a minute to evaluate. Luckily the GCL te

I had my own qualms with the language itself too. My team had very complex Borg configs, so complex they took more than a minute to evaluate. Luckily the GCL team at the time was working on a new interpreter (gclx? IIRC), which was indeed much faster (I wrote a mandelbrot PNG generator in pure GCL to prove the big speedup and convince my team that switching was worth the effort). Unfortunately there was no formal spec of the GCL language, so the new impl was based IIRC on reverse engineering the spec from the first implementation of the interpreter. It turned out our configs hit several cases where the original behaviour was either unsound (and thus the new impl sacrificed backwards compat) or we hit a bug in the new impl. The main problem with the language (as opposed as issues with the implementations) was that finding the root of those behaviour differences was very hard. It was very hard to follow where the variables came from. The GCL scoping rules (and lazy evaluation) were indeed very unfriendly for debugging. This was an extreme case of a pain that was felt on a daily basis by a lot of people I've been talking to.