hasql-dynamic-statements

Library extending Hasql with a composable API for building SQL statements dynamically.

The core abstraction is Snippet, which allows you to construct SQL statements with parameters injected in-place, automatically handling placeholders and encoder matching. This is particularly useful when the structure of your SQL depends on runtime parameters.

Key features:

• Composable SQL snippets using Semigroup and Monoid instances
• Automatic placeholder generation and parameter encoding
• Type-safe parameter injection with implicit encoder derivation
• Protection against common SQL construction bugs
• Support for conditional SQL structure based on parameters

Example:

selectSubstring :: Text -> Maybe Int32 -> Maybe Int32 -> Snippet
selectSubstring string from to =
  "select substring(" <> param string <>
  foldMap (\x -> " from " <> param x) from <>
  foldMap (\x -> " for " <> param x) to <>
  ")"