But the whole point of Haskell is to make claims that confuse the unitiated, isn't it? Because that's excactly what every tutorial that claims "Haksell is a pure langauge" is doing when it then goes on to say "Haskell can do I/O" without explaining that unlike every other language the unitiated reader has ever encountered, Haskellers have chosen to define "the langauge" in such a way as to exclude "the runtime".

I really don't get why this point is not made clear in all Haskell discussions up-front, but instead Haskellers insist on repeating the empty mantra "Haskell is a pure language" as if they were using the term "language" in the standard way rather than redefining it in a carefully constructed way so as to make their claim true.

This is terrible pedagogy on par with people who introduce negative generalized temperature or resistance without first explaining that they are generalizing the concept. And it obscures one of the coolest aspects of Haskell, which is that it is an impure language (using "language" in the standard way, which always includes the runtime) that has very cleverly packaged its impurity such that reasoning about the code still gets most of the advantages of purity.

"Haskell has a pure syntax that is interpreted by an impure runtime" is more accurate and far less confusing.