[Haskell-cafe] strict, lazy, non-strict, eager

[Albert Y. C. Lai]

Most individuals of the Haskell community have long been maintaining a 
cognitive dissonance; some cases turn into plain hypocrisy. You might 
excuse it for its ancient and prominent origin: Richard Bird and/or 
Philip Wadler themselves wrote like "it is too lazy", "make it more 
strict" 13 years ago and surely more. But perpetuating it is not helping.

I have not written this complaint until now because I have been waiting 
for unmistakable evidence, a smoking gun, a red hand so caught that you 
cannot explain away, for example you cannot explain that "one sentence 
is from one person, the other sentence is from a different person".

So, on IRC in #haskell, from the same person, speaking on the same topic 
in the same context, in the same interval of 3 minutes (the first two 
sentences in the same minute):

1. a function f is strict if  f ⊥ = ⊥
2. ⊥ represents any computation which does not terminate, i.e. an 
exception or an infinite loop
3. "strict" describes the denotational semantics

People, could you please make up your mind already? It has been more 
than 13 years.

Denotational semantics:
A. There are no computational steps. There is no termination, and there 
is no non-termination, since there are no steps to finish, and no steps 
to keep going.
B. ⊥ represents "no information", not "non-termination". There is no 
"non-termination" to represent.
C. fix id = ⊥ because ⊥ is the least fixed point of id, not because fix 
id non-terminates. There is nothing to terminate or non-terminate.
D. You say strict, more strict, less strict; non-strict, more 
non-strict, less non-strict. You don't say eager, and you don't say lazy.

Operational semantics:
A. There is no ⊥; it does not appear in any sequence of computational 
steps, finitely long or infinitely long.
B. You say eager, more eager, less eager; lazy, more lazy, less lazy; or 
speculative, more speculative, less speculative; or any other adjectives 
for evaluation strategies. You don't say strict, and you don't say 
non-strict.

"Semantics", "semantically speaking":
A. Which semantics, which semantically? There are two.
B. Actually there are more, but apparently two is already enough to 
cause all kinds of incoherent statements. If I draw your attention to 
algebraic semantics, will you start saying "it is too lazy, need to make 
it more idempotent"?