JuliaCon 2017 | The State of the Type System | Jeff Bezanson

where Syntax

• Where questions
• What is the main point of “where”?
• where in function definitions in julia-0.6
• Vector of dictionaries of different types in julia 0.6
• Anybody else find the new where syntax less than satisfactory?
• Help with where syntax in Julia v0.6

  Pits & Falls

• Return type assertions with type parameters
• “where” - where?
• Why is where syntax in Julia sensitive to new-line?

Invariant

• Null and Array of T question

Triangular Dispatch

• Can I use a subtype of a function parameter in the function definition?
• Julia fails to multiple dispatch

  Related Issues

• triangular dispatch (left-to-right template parameter chaining) #3766
• Feature request: Add syntactic sugar for covariant actual type parameters #6984

Union

• Why Union{} <: Tuple?

Issues

• type system design iteration #8974
• type system revision and new subtype algorithm #18457
• syntactic sugar Foo{<:Bar} for Foo{T} where T<:Bar#20414
• Proposal: Defer calculation of field types until type parameters are known #18466