wireform-flatbuffers

wireform-flatbuffers implements Google FlatBuffers, a zero-copy serialization format designed for game engines, mobile apps, and real-time inference serving. FlatBuffers lay out tables with vtables that index field offsets, keeping scalars inline and strings or sub-tables behind indirection. Use this package when you need to read large buffers without deserializing the entire message, or when sharing the builder infrastructure with Arrow IPC.

Key features

• Typeclass API via ToFlatBuffers and FromFlatBuffers with Template Haskell deriving
• FlatBuffers IDL parser and codegen from .fbs schema files
• Vtable-based wire layout with inline scalars and offset-indirected collections
• Zero-copy view/reader via FlatBuffers.View for schema-known access patterns
• Shared builder with Arrow IPC for cross-format buffer construction
• QuasiQuoter for inline [flatbuffers| ... |] schemas

Basic usage

Derive instances for your table types, then encode and decode through the value-level codec:

{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE TemplateHaskell #-}

import FlatBuffers.Decode qualified as FBD
import FlatBuffers.Derive (ToFlatBuffers (..), FromFlatBuffers (..), deriveFlatBuffers, deriveView)
import FlatBuffers.Encode qualified as FBE
import FlatBuffers.Parser (parseFlatBuffers)
import FlatBuffers.Codec (CompiledSchema, compileSchema)
import Data.Int (Int32)
import Data.Text (Text)
import GHC.Generics (Generic)

data Widget = Widget
  { widgetName  :: !Text
  , widgetCount :: !Int32
  , widgetPrice :: !Double
  }
  deriving stock (Show, Eq, Generic)

$(deriveFlatBuffers ''Widget)
$(deriveView ''Widget)

widgetSchema :: Either String CompiledSchema
widgetSchema = parseFlatBuffers "table Widget { name:string; count:int; price:double; } root_type Widget;" >>= compileSchema

encodeWidget :: Widget -> Either String ByteString
encodeWidget widget = widgetSchema >>= (\schema -> FBE.encodeWith schema (toFlatBuffers widget))

decodeWidget :: ByteString -> Either String Widget
decodeWidget bs = do
  schema <- widgetSchema
  val <- FBD.decodeWith schema bs
  fromFlatBuffers val

sample :: Widget
sample = Widget "wireform" 42 2.718

roundTrip :: Either String Widget
roundTrip = encodeWidget sample >>= decodeWidget

Dynamic encode/decode require a parsed or compiled schema; values follow declaration order. decodeWith materializes a typed Value tree and validates references, alignment, and required fields. Defaults and optional scalar presence come from that schema.

For zero-copy reads on known schemas, use the view layer after encoding:

import FlatBuffers.View (decodeRoot)

readWidget :: ByteString -> Either String Widget
readWidget = decodeRoot

Generate types from .fbs files:

{-# LANGUAGE TemplateHaskell #-}
import FlatBuffers.QQ (fbs)

[fbs|
  table Widget {
    name:string;
    count:int;
    price:double;
  }
  root_type Widget;
|]

wireform-gen flatbuffers -i schema.fbs -o src/Gen/

Performance

Schema-directed dynamic encode/decode

Operation	encode	decode	ratio
Person table	1222 ns	185 ns	0.15x
Person[100] vector	99387 ns	17627 ns	0.18x

_{Last run 2026-11-06 10:08:02 UTC. GHC 9.10.3, Apple Silicon, criterion 1.6.5. Full Value materialization; compiled schemas reused.}

Like Cap’n Proto, FlatBuffers decode is a zero-copy cursor. The decode cost is near-constant because only the root table offset is resolved; field access is lazy pointer arithmetic into the original buffer. Encode is proportional to the number of fields and vector elements.

The chart and table above are regenerated by wireform-stats from wireform-flatbuffers/bench-results/summary/flatbuffers-encode-decode.json — the same source the README chart is built from.

Notable modules

Module	Purpose
FlatBuffers.Derive	ToFlatBuffers / FromFlatBuffers and deriveFlatBuffers
FlatBuffers.Encode / FlatBuffers.Decode	High-level encoder and value-tree decoder
FlatBuffers.View	Zero-copy cursor access for schema-known tables
FlatBuffers.Reader	Low-level pointer-walking decoder
FlatBuffers.Builder	Vtable and offset builder
FlatBuffers.Value	Dynamic untyped Value ADT
FlatBuffers.Schema / FlatBuffers.Parser	Schema AST and .fbs parser
FlatBuffers.CodeGen / FlatBuffers.QQ	Haskell codegen and quasiquoter
FlatBuffers.Registry	Runtime schema registry