{"id":368369,"date":"2017-03-02T01:29:11","date_gmt":"2017-03-02T09:29:11","guid":{"rendered":"https:\/\/www.microsoft.com\/en-us\/research\/?post_type=msr-research-item&#038;p=368369"},"modified":"2018-10-16T20:10:37","modified_gmt":"2018-10-17T03:10:37","slug":"theory-practice-demand-analysis-haskell","status":"publish","type":"msr-research-item","link":"https:\/\/www.microsoft.com\/en-us\/research\/publication\/theory-practice-demand-analysis-haskell\/","title":{"rendered":"Theory and practice of demand analysis in Haskell"},"content":{"rendered":"<p>Any decent optimising compiler for a lazy language like Haskell must include a strictness analyser. The results of this analysis allow the compiler to use call-by-value instead of call-by-need, and that leads to big performance improvements. It turns out that strictness analysis is an interesting problem from a theoretical point of view, and the 1980\u2019s saw a huge rash of papers on the subject. There were fewer, many, many fewer, papers that described real implementations.<\/p>\n<p>This paper presents the fruits of a decade-long experience with strictness analysis, in the context of the Glasgow Haskell Compiler, an optimising compiler for Haskell. In particular, we recently re-engineered the existing strictness analyser that used forward abstract interpretation, replacing it with a new one that uses backward analysis instead.<\/p>\n<p>This unpublished draft is better explained, and much closer to the actual implementation in GHC, than <a href=\"https:\/\/www.microsoft.com\/en-us\/research\/publication\/demand-analysis\/\">our earlier\u00a0version<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Any decent optimising compiler for a lazy language like Haskell must include a strictness analyser. The results of this analysis allow the compiler to use call-by-value instead of call-by-need, and that leads to big performance improvements. It turns out that strictness analysis is an interesting problem from a theoretical point of view, and the 1980\u2019s 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