labels vs vinyl vs record vs lens

comparison.md

labels vs vinyl vs record vs lens

Advantages and disadvantages of each are explored here.

vinyl

Pros

• Support arbitrary number of fields
• Supports projecting and narrow and things like that quite well
• Apparently supports lens
• Field order doesn't change the type

Cons

• Requires you to declare fields ahead of time

• Apparently takes up runtime space

• Types are fairly complex

• Creating values is kind of a drag (lots of operators and nil):

        (SName =:: "tucker")
     :& (SAge =:: 9)
     :& (SSleeping =:: True)
     :& (SMaster =:: jon)
     :& RNil
  

• Likely supports projection

Unclear

• Type inference is good?
• Has rows? Like Has field record => record -> .... Unclear from the docs.

labels

Pros

• Does not require you to declare fields ahead of time
• No runtime overhead over regular tuples
• Supports projection
• Supports lenses via lens #foo e.g. set (lens #foo . lens #bar) .. ..
• Type inference is good
• Type signatures are short: ("foo" := Int, "bar" := String)
• Creating values is trivial: (#foo := 123, #bar := "hi")
• Supports rows: (Has "foo" r, Has "bar" r) => r -> ...

Cons

• Field order matters
• Instance explosion for Has class: haddocks
• Only supports 24 fields at a time

record

Pros

• A limited number of fields (like labels)
• Does not require you to declare fields ahead of time
• Types are simple
• Supports (or: requires) lenses

Cons

• Field order matters
• Doesn't require declaring fields ahead of time
• Requires a preprocessor (for creating types, values, updates, etc.)
• Type inference is good
• Value creation is pretty clean syntax
• Doesn't support projection/narrowing/reshaping

Unclear

• Supports rows? Unknown

lens

Pros

• Supports composable setters/getters
• Supports "rows" like (HasName r, HasAge r) => r -> ...

Cons

• Requires declaring things ahead of time
• Isn't really a record system
• Doesn't support projection/narrowing/reshaping