>I don't know what you mean about an "informal spec", the the full formal specification of Python (the language)
I think GP meant "informal" in the sense that python wasn't originally meant to be a multi-implementation language. Though the oldest alternative implementation goes back to 1997, alternatives were always, until relativel recently, second class. I don't have the tools or the time to quantify what I mean by "recently" or "second class", but I hope you know what I mean.
The single biggest marker of being "second class" that I do know of is how the new features always gets introduced first by Cpython, then every other implementation plays catch up. This is unheard of in true multi-implementation languages, what I have in mind is C, C++, Java and Javascript. I'm sure there are plenty more, but those just, off the top of my head, are the most prominent languages whose features are introduced first in completely implementation-agnostic way, then all implementations start racing to get it complete.
I don't mean to say that Cpython maintainers just wake up in the morning and decide to add new syntax or semantics to the language, PEP documents are quite formal and implementation-agnostic, but I always had the impression it's something by Cpython devs for Cpython devs, and supporting that is how a Cpython implementation always appear first and other implementations lag behind by a varying amounts.
I think GP meant "informal" in the sense that python wasn't originally meant to be a multi-implementation language. Though the oldest alternative implementation goes back to 1997, alternatives were always, until relativel recently, second class. I don't have the tools or the time to quantify what I mean by "recently" or "second class", but I hope you know what I mean.
The single biggest marker of being "second class" that I do know of is how the new features always gets introduced first by Cpython, then every other implementation plays catch up. This is unheard of in true multi-implementation languages, what I have in mind is C, C++, Java and Javascript. I'm sure there are plenty more, but those just, off the top of my head, are the most prominent languages whose features are introduced first in completely implementation-agnostic way, then all implementations start racing to get it complete.
I don't mean to say that Cpython maintainers just wake up in the morning and decide to add new syntax or semantics to the language, PEP documents are quite formal and implementation-agnostic, but I always had the impression it's something by Cpython devs for Cpython devs, and supporting that is how a Cpython implementation always appear first and other implementations lag behind by a varying amounts.