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claude-codedevops

Claude-skill-registry create-haskell-bazel-target

Create a target for haskell application.

install
source · Clone the upstream repo
git clone https://github.com/majiayu000/claude-skill-registry
Claude Code · Install into ~/.claude/skills/
T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/create-haskell-bazel-target" ~/.claude/skills/majiayu000-claude-skill-registry-create-haskell-bazel-target && rm -rf "$T"
manifest: skills/data/create-haskell-bazel-target/SKILL.md
tags
#haskell#bazel#dependency-management#build-system
source content

Create Haskell Bazel Target

Instruction

  1. When creating a binary use haskell_binary
  2. When creating a test use haskell_test
  3. When creating a library use haskell_library
  4. Always want to include //:base for dependencies
  5. Any other 3rd party package from hackage, need to use either @stackage or @stackage_alt depending on the packages needed

CRITICAL: Dependency Prefix Rules

Core GHC packages MUST use 

//:
prefix (NOT 
@stackage//:
)

Core GHC Packages (use 
//:package-name
)

  • //:base
    - Always required
  • //:bytestring
  • //:containers
  • //:directory
  • //:filepath
  • //:text
  • //:time
  • //:array
  • //:deepseq
  • //:process
  • //:mtl
  • //:transformers

Third-Party Packages (use 
@stackage//:package-name
)

  • @stackage//:aeson
  • @stackage//:yaml
  • @stackage//:cmark
  • @stackage//:QuickCheck
  • @stackage//:hspec
  • @stackage//:http-conduit
  • @stackage//:vector
  • @stackage//:random
  • Any package not bundled with GHC

Common Error

Using 

@stackage//:base
or 
@stackage//:text
will cause visibility errors:

ERROR: target '@@rules_haskell~~stack_snapshot~stackage//:base' is not visible from target

Fix: Replace 

@stackage//:base
with 
//:base
(same for text, containers, etc.)

Custom Dependencies in non_module_deps.bzl

When configuring custom Hackage packages in 

non_module_deps.bzl
, ensure glob patterns match the directory structure AFTER 
strip_prefix
is applied:

WRONG:

http_archive(
    name = "libyaml",
    urls = ["https://hackage.haskell.org/package/libyaml-0.1.4/libyaml-0.1.4.tar.gz"],
    strip_prefix = "libyaml-0.1.4",  # This strips the directory
    build_file_content = """
haskell_cabal_library(
    name = "libyaml",
    srcs = glob(["libyaml-0.1.4/**/*"]),  # ❌ WRONG - directory already stripped!
    ...
)
"""
)

CORRECT:

http_archive(
    name = "libyaml",
    urls = ["https://hackage.haskell.org/package/libyaml-0.1.4/libyaml-0.1.4.tar.gz"],
    strip_prefix = "libyaml-0.1.4",  # This strips the directory
    build_file_content = """
haskell_cabal_library(
    name = "libyaml",
    srcs = glob(["**/*"]),  # ✓ CORRECT - files are at root after strip
    ...
)
"""
)

Without strip_prefix:

http_archive(
    name = "yaml",
    urls = ["https://hackage.haskell.org/package/yaml-0.11.11.2/yaml-0.11.11.2.tar.gz"],
    # No strip_prefix - directory preserved
    build_file_content = """
haskell_cabal_library(
    name = "yaml",
    srcs = glob(["yaml-0.11.11.2/**/*"]),  # ✓ CORRECT - directory exists
    ...
)
"""
)

Checklist

  1. Check if it is already declared in the MODULE.bazel
  2. Check if the target is build clean
  3. When adding custom dependencies to non_module_deps.bzl, ensure glob patterns match the post-strip_prefix directory structure
  4. When adding data as a bazel dependencies, the relative path needs to be from the repository root,
    haskell_test(
        name = "hackage-doc-cli-test",
        srcs = glob(["**/*.hs"]),
        data = glob(["Fixtures/**/*"])
    )

source code

haskell/app/hackage-doc-cli/test/Fixtures/aeson-package.json

Examples of Bazel Target

haskell_binary Example

# Neural network from scratch application
haskell_binary(
    name = "neural-network",
    srcs = [":Main.hs"],
    deps = [
        "//:base",                           # Core GHC package
        "//haskell/libs/neural-network",     # Local library
        "@stackage//:random",                # Third-party package
    ],
)

haskell_library Example

haskell_library(
    name = "neural-network",
    srcs = glob(["src/**/*.hs"]),
    src_strip_prefix = "src",
    ghcopts = ["-XRecordWildCards"],
    visibility = ["//visibility:public"],
    deps = [
        "//:base",                # Core GHC package
        "@stackage//:vector",     # Third-party package
        "@stackage//:random",     # Third-party package
    ],
)

haskell_test Example

haskell_test(
    name = "unit-tests",
    srcs = glob(["test/**/*.hs"]),
    src_strip_prefix = "test",
    deps = [
        ":my-library",            # Local library being tested
        "//:base",                # Core GHC package
        "//:text",                # Core GHC package
        "//:containers",          # Core GHC package
        "@stackage//:QuickCheck", # Third-party test framework
        "@stackage//:hspec",      # Third-party test framework
    ],
)

Library with Multiple Core Dependencies

haskell_library(
    name = "rpg-ruleset-core",
    srcs = glob(["src/**/*.hs"]),
    src_strip_prefix = "src",
    visibility = ["//visibility:public"],
    deps = [
        # Core GHC packages (use //:)
        "//:base",
        "//:bytestring",
        "//:containers",
        "//:directory",
        "//:filepath",
        "//:text",
        "//:time",

        # Third-party packages (use @stackage//:)
        "@stackage//:aeson",
        "@stackage//:cmark",
        "@stackage//:yaml",
    ],
)