Data.ByteString.Builder.Internal: export some data constructors

[fumieval]

Fixes #51?

[sjakobi]

LGTM & many thanks, @fumieval! :)

[fumieval]

Sorry, I was confused; #51 was actually about primMapListBounded, which is already exported in the current version. The haddock problem is addressed in #248

[Bodigrim]

I would rather refrain from exposing more internals, unless there is a direct reason for.

[sjakobi]

I would rather refrain from exposing more internals, unless there is a direct reason for.

I generally don't mind exposing internals, but I think the question is what stability guarantees they are exposed with (#253).

In the case of these constructors I in fact don't see a strong motivation to expose them:

• BuildStep is actually just a type synonym – the added (..) doesn't change anything
• To destructure Builder, users can rely on runBuilderWith. To construct a Builder, they can use builder.
• For Put we offer put and runPut.

So maybe we should try making progress with #253 before we expose the Builder and Put constructors.

@hsyl20 What do you think?

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@fumieval The documentation fixes in 61442d3 are definitely welcome though! Would you mind putting these up in a separate PR? :)

Exposing internals needs more discussion and better motivation

[fumieval]

I moved the documentation fix into #248 while it's open.

BuildStep(..) was my oversight; I actually meant BuildSignal. I wanted to use the data constructors when creating a custom consumer of Builder, but since there's fillWithBuildStep it is not necessary. I'm happy to close this.