hasql-postgresql-types: Integration of "hasql" with "postgresql-types"
Provides automatic encoder and decoder generation for "hasql", supporting all PostgreSQL types defined in the "postgresql-types" package.
Motivation
The standard "hasql" codecs use common Haskell types like Text, DiffTime, UTCTime, etc. However these types do not always map precisely to PostgreSQL types. E.g., the PostgreSQL interval type carries information about months, years and microseconds, while the Haskell DiffTime type only represents a time difference in picoseconds. Such mismatches can lead to data loss or unexpected behavior. The "postgresql-types" library addresses such issues by providing precise Haskell representations for PostgreSQL types. This package integrates it with "hasql". It also provides a class-based polymorphic interface for defining "hasql" Value codecs.
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- hasql-postgresql-types-0.1.0.1.tar.gz [browse] (Cabal source package)
- Package description (as included in the package)
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| Versions [RSS] | 0.1, 0.1.0.1 |
|---|---|
| Dependencies | base (>=4.11 && <5), hasql (>=1.10.1 && <1.11), postgresql-types-algebra (>=0.1 && <0.2), ptr-peeker (>=0.1.0.1 && <0.2), ptr-poker (>=0.1.3 && <0.2), tagged (>=0.8.9 && <0.9), text-builder (>=1.0.0.4 && <1.1) [details] |
| License | MIT |
| Copyright | (c) 2026, Nikita Volkov |
| Author | Nikita Volkov <nikita.y.volkov@mail.ru> |
| Maintainer | Nikita Volkov <nikita.y.volkov@mail.ru> |
| Uploaded | by NikitaVolkov at 2026-01-23T09:06:53Z |
| Category | PostgreSQL, Codecs, Hasql |
| Home page | https://github.com/nikita-volkov/hasql-postgresql-types |
| Bug tracker | https://github.com/nikita-volkov/hasql-postgresql-types/issues |
| Source repo | head: git clone https://github.com/nikita-volkov/hasql-postgresql-types |
| Distributions | |
| Downloads | 3 total (3 in the last 30 days) |
| Rating | (no votes yet) [estimated by Bayesian average] |
| Your Rating | |
| Status | Docs uploaded by user Build status unknown [no reports yet] |
Readme for hasql-postgresql-types-0.1.0.1
[back to package description]hasql-postgresql-types
Integration of "hasql" with "postgresql-types" via the IsScalar typeclass from "postgresql-types-algebra".
Provides automatic encoder and decoder generation for precise PostgreSQL scalar types.
Motivation
The standard "hasql" codecs use common Haskell types like Text, DiffTime, UTCTime, etc. However these types do not always map precisely to PostgreSQL types. E.g., the PostgreSQL interval type carries information about months, years and microseconds, while the Haskell DiffTime type only represents a time difference in picoseconds. Such mismatches can lead to data loss or unexpected behavior. The "postgresql-types" library addresses such issues by providing precise Haskell representations for PostgreSQL types. This package integrates it with "hasql". It also provides a class-based polymorphic interface for defining "hasql" Value codecs.
Usage
import Hasql.PostgresqlTypes (encoder, decoder)
import qualified PostgresqlTypes as Pt
import qualified Hasql.Statement as Statement
import qualified Hasql.Encoders as Encoders
import qualified Hasql.Decoders as Decoders
myStatement :: Statement.Statement Pt.Timestamptz [Pt.Timestamptz]
myStatement = Statement.preparable sql enc dec
where
sql = "SELECT $1::timestamptz"
enc = Encoders.param (Encoders.nonNullable encoder)
dec = Decoders.rowList (Decoders.column (Decoders.nonNullable decoder))