Sequential ordering of evaluation

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The seq primitive, despite its name, is not required to evaluate its parameters in some predefined order, according to the Haskell 2010 Report. For parallel programming, sometimes a variant of seq is needed with such an ordering:

While we focus mainly on the implementation, our work has had some impact on the programming model: we identify the need for pseq as well as seq (Section 2.1), and we isolated a signficant difficulty in the "strategies" approach to writing parallel programs (Section 7).

Instead of two or more similar primitives with similar purposes, extend the existing seq primitive with the traditional ordering of evaluation for its parameters - first, then second; with the role of simple strictness-control being performed by a new primitive with a more appropriate name e.g. amid, in Strictness without ordering, or confusion.

Atravers 02:00, 7 January 2019 (UTC)