[Haskell-cafe] Preventing sharing

Oleg oleg at okmij.org
Tue Dec 22 12:31:56 UTC 2015

Henk-Jan van Tuyl wrote:
> In paper "Why Functional Programming Matters"[0], John Hughes shows how
> lazy functional programming can be used for better modularity. A more
> precise title for the paper would be "Why Lazy Functional Programming
> Matters".

The first paragraph of our paper (published 3 years ago)
is as follows

    Lazy evaluation is regarded as one of the main reasons why functional
    programming matters \cite{hughes:matters-cj}.  Lazy evaluation lets us
    write \emph{producers} and \emph{consumers} separately, whereas the
    two are inextricably intertwined in a call-by-value language.  This
    separation allows a modular style of programming, in which a variety
    of producers, consumers, and transformers can readily be ``plugged
    together.'' Lazy evaluation is also an elegant implementation of a
    form of coroutines, suspending and resuming computations based on the
    demand for values, giving us memory-efficient, incremental computation
    `for free'

But do read the next paragraph and the rest of the paper, and other
articles on the web site

Our conclusion is that the modularity benefit of lazy evaluation can
be held without lazy evaluation, gaining the predictability of the
space and time behavior.

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