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Specify function subtyping #28

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jclark opened this issue Mar 24, 2019 · 2 comments
Closed

Specify function subtyping #28

jclark opened this issue Mar 24, 2019 · 2 comments
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Area/Lang Relates to the Ballerina language specification design/incomplete Part of design not yet worked out
Milestone
2019R1

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@jclark
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jclark commented Mar 24, 2019 •
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The spec does not specify exactly how function subtyping should work.

Basic principle is that functions should be covariant in return type and contravariant in parameter types. Default values should not affect subtyping.

Ideally we want to define this in terms of shapes (ie type denotes set of shapes, and subtype means subset of denoted set of shapes).

Relates to #27
@jclark jclark added Area/Lang Relates to the Ballerina language specification design/incomplete Part of design not yet worked out labels Mar 24, 2019
@jclark jclark added this to the 2019R2 milestone Mar 24, 2019
@jclark jclark mentioned this issue Mar 26, 2019
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@jclark jclark modified the milestones: 2019R2, 2019R1 Mar 28, 2019
jclark added a commit that referenced this issue Apr 1, 2019
@jclark
Improved design for named and default function arguments
f9ca76c 
Fixes #27, #25, #26. Starts on #33 and #28. Finishes #11.
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jclark commented Apr 1, 2019

Mostly done now. Remains to define it in terms of shapes.

@jclark jclark closed this as completed in d7e91a8 Apr 28, 2019
@jclark jclark reopened this Apr 28, 2019
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jclark commented Apr 29, 2019

I have separated the shape aspect into a separate issue #86.

@jclark jclark closed this as completed Apr 29, 2019
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