On 08/29/2018 04:01 PM, Walter Bright wrote:
On 8/29/2018 10:50 AM, Timon Gehr wrote:
D const/immutable is stronger than immutability in Haskell (which is
usually _lazy_).
I know Haskell is lazy, but don't see the connection with a weaker
immutability guarantee. In any case, isn't immutability a precept of FP?
I think the point is that it disallows less, and permits more, all
without breaking immutability.
Ie, lazy immutable *can* be changed, albiet once and only once in a very
specific circumstance: When transitioning from uninitialized to
initialized. AIUI, D only has this "the immutable is in-scope, but can
still be initialized" state within constructors, whereas (it sounds
like) Haskell allows it anywhere.
It's like strong-pure vs weak-pure: Both enforce the same purity
guarantees, but weak-pure is less restrictive and more expressive.
