Improve typing for ==, != expressions #5840
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anandthakker
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jfirebaugh
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| possibleOutputs() { | ||
| return this.lhs.possibleOutputs().concat(this.rhs.possibleOutputs()); |
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Should be return [true, false].
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GL JS change: mapbox/mapbox-gl-js#5840 GL Native issue: #10678
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GL JS change: mapbox/mapbox-gl-js#5840 GL Native issue: #10678
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Closes #5761
Closes #5835
The overloads of == and != are now effectively:
(T1: Comparable, T2: Comparable) => boolean { T1 == T2 }(Comparable, value) => boolean(value, Comparable) => booleanWhere
Comparable = string | number | boolean | null, and evaluation semantics for thevaluecases are equivalent to Javascript's strict equality (===/!==), i.e., when thevalueargument's type doesn't match that of theComparableargument,==evaluates tofalse,!=to true.An alternative, stricter approach we discussed was to keep the signatures above, but to produce an runtime error in the case of a type mismatch between the
valueandComparablearguments -- essentially inserting a type assertion wrapper around thevalueargument. We went with the less strict approach because:==,!=filters==/!=to test fornull(How to test for nulls with new expression syntax? #5761)