Moritz Kiefer 8ff347d8ed Expand type synonyms lazily (#11282) ... * Expand type synonyms lazily We really only need to expand type synonyms in two cases: 1. When pattern matching e.g. to check that a projection on a struct really happens on a struct. In this case we can first check if we have a struct in which case we don’t need to expand anything. If we don’t, we can expand afterwards. 2. When checking two types for alphaequivalence. This PR goes for the simplest solution: First check alphaequivalence without expanding anything treating type synonyms nominally. Then if that fails expand everything and check again. We could be more clever and interleave expansion with checking for alphaequivalence but this seems to give us most of the performance benefits while keeping the logic very simple. On my local laptop this speeds up typechecking of the full DAR from 380ms to 176ms so roughly a 2x improvement. For comparison: The Daml-LF 1.7 DAR which still relies on nonminal typechecking of typeclasses everywhere takes 110ms. So we are still leaving something on the table here but we’re much closer. I think this also gets us to the point where speedy compilation is slower than typechecking but I need to verify that again. changelog_begin changelog_end * Apply suggestions from code review Co-authored-by: Remy <remy.haemmerle@daml.com> * fix biuld changelog_begin changelog_end Co-authored-by: Remy <remy.haemmerle@daml.com>		2021-10-19 20:48:32 +00:00
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src	Expand type synonyms lazily (#11282)	2021-10-19 20:48:32 +00:00
BUILD.bazel	Add an LF typechecking benchmark (#11276)	2021-10-18 12:53:17 +00:00