Why <: and not <=: ?

[Dave]

If I understand typeclass with an upper boundery well then:

A <: B

means

A is a subtype of B or B itself (so B is inclusive)

Wouldn't

A<=: B

be more intuitive (I think the mathematical notation is : ∇t ⊆ τ. t →
t where t is A and τ is B (hopefully the unicode characters are
encoded well otherwise there is some mojibake in this post))

[Donna Malayeri]

In mathematics, yes, but in type systems, the less-than-equal sign or <: are used interchangeably, with the latter being far more common. It is understood that <: is a reflexive, transitive preorder and would therefore be equivalent to a symbol with an equal sign.

Donna

[Dave]

Thanks, Donna.