[Haskell-cafe] Strict and non-strict vs eager and lazy, was C onfused about Cyclic struture

Bayley, Alistair Alistair_Bayley at ldn.invesco.com
Mon Jul 18 10:19:14 EDT 2005

> From: Jerzy Karczmarczuk [mailto:karczma at info.unicaen.fr] 
> Bernard Pope wrote:
> >I'll be a little bit pedantic here. Haskell, the language definition,
> >does not prescribe lazy evaluation. It says that the language is
> >non-strict. Lazy evaluation is an implementation technique which
> >satisfies non-strict semantics, but it is not the only 
> technique which
> >does this.
> >  
> >
> This pedantry is renewed periodically.
> It is a pity that nobody ever writes anything about that other
> methods of implementation of non-strictness, nor about the
> languages which use those methods.
> I believe it might do some good to people who learn functional
> programming in general, and Haskell in particular.
> Any takers?

Not a taker (yet - where can I find information about non-lazy
implementation of non-strict languages? From Google so far: speculative
evaluation (Eager Haskell), call-by-name vs call-by-need.)

Wikipedia frustratingly hints that "other evaluation strategies are
possible", but that's all it says:


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