Data.Bytes.Builder.Template

Quasiquotation for byte builders.

Documentation

bldr :: QuasiQuoter

A quasiquoter for builders. Haskell expressions are interpolated with backticks, and the ToBuilder class is used to convert them to builders. Several common escape sequences for whitespace and control characters are recongized. Consider the following expression, where the binding partition has type Word32:

[templ|[WARN] Partition `partition` has invalid data.\n|]

This expression has type Builder and expands to:

Builder.cstringLen (Ptr "[WARN] Partition "#, 17) <>
Builder.toBuilder partition <>
Builder.cstringLen (Ptr " has invalid data.\n"#, 19)

The ToBuilder instance for Word32 uses decimal encoding, so this would result in the following if partition was 42 (with a newline character at the end):

[WARN] Partition 42 has invalid data.

In the future, a more sophisticated bbldr variant will be added that will support expressions where the maximum length of the entire builder can be computed at compile time.