Elixir's gradual type system cannot change the asymptotic complexity of your programs. The design explicitly rules out mechanism that causes slowdowns in other gradual type systems (runtime casts at static/dynamic boundaries)

Most gradual type systems insert coercions when values cross the types/untyped boundary (checking every element of a list, wrapping values in typed proxies, etc) but Elixir's team published a "strong arrows" result specifically to achieve soundness without those runtime checks. The bytecode the compiler emits is semantically identical to untyped code.

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dnautics 3 hours ago | parent [-]

i think the design can push people into writing unnecessary matches/guards just to trigger the typechecker.

that said, I'm a fan

	▲	josevalim an hour ago \| parent [-]
		That can be a concern indeed but it is worth noting that strong arrows compose/propagate. So if you have a function without guards that calls a function that guards on said types, the caller is also strong! We will likely have mechanisms to measure "strength" when we introduce type annotations.