Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[0.5.0] - 2026-04-13

Added

• Effect polymorphism. Effect variables (lowercase tokens inside brackets) let one signature express that a function propagates whatever effects its callback has:

  effects myapp/validation.validate_range(to_error: [e]) : [e]
  effects myapp.map_with_log(f: [e]) : [Stdout, e]
  

  graded infer produces polymorphic signatures automatically when a function calls a parameter annotated with a fn(...) -> ... type. The variable is named after the parameter.

• Call-site substitution. At each call site, effect variables bind to the concrete effects of the argument passed: a function reference resolves via the knowledge base, a type constructor is pure, the caller’s own bounded parameter uses that bound’s effects, and anything else falls back to [Unknown]. Works with both labeled (validate_range(42, to_error: OutOfRange)) and positional (validate_range(42, OutOfRange)) arguments. Covers cross-module calls, same-module local helpers, and calls into dependencies.

• Dependency parameter positions. graded now parses each build/packages/<dep>/src/ tree with glance to learn dependency function signatures. Positional arguments to polymorphic dep functions resolve correctly without requiring labels.

• Wildcard [_]. Documented in the README’s new Effect set syntax section. Wildcard is the top of the effect lattice — [_] as a declared budget permits any effects. Useful for entrypoints.

Changed

• Violation messages now include a hint when the actual effects contain unresolved effect variables, suggesting a check bound or a concrete argument to bind against.

[0.4.2] - 2026-04-12

Fixed

• Added gleam/dynamic/decode to the gleam_stdlib catalog. Decoder combinators (field, optional_field, string, int, list, dict, success, etc.) are pure but were resolving as [Unknown].
• graded infer now resolves cross-module type constructors as pure, matching the existing handling for unqualified constructors. Previously, calls like types.NotFound(id) from a sibling project module were marked [Unknown] because constructors aren’t tracked in the knowledge base and the defining project module isn’t in pure_modules. Constructors are pure by Gleam’s syntactic rules — an uppercase-initial label after a . is always a type variant — so the qualified call, qualified pipe target, and qualified value-position branches in the extractor now short-circuit the same way the unqualified path does. Side-effecting expressions inside a constructor’s argument list (e.g. NotFound(io.println(x))) still propagate.

[0.4.1] - 2026-04-11

Fixed

• graded infer now reads the spec file’s external effects and type field declarations into the knowledge base before walking the import graph. Previously these were only consumed by graded check, so functions calling into a third-party module declared pure via external effects were still inferred as [Unknown]. The check pass passed but the inferred spec stayed noisy.

[0.4.0] - 2026-04-10

Added

• [tools.graded] config table in gleam.toml, with spec_file and cache_dir fields.
• graded/internal/topo module: standalone topological sort over a string-keyed dependency graph, with property and unit tests.

Changed

• Project annotations have moved out of priv/graded/. Each Gleam package now has a single spec file at the project root (default name <package_name>.graded, configurable via [tools.graded].spec_file in gleam.toml) holding the public-API effects, check invariants, external effects hints, and type field annotations. Per-module inferred effects (public + private) live in build/.graded/ as a regenerable build cache (configurable via [tools.graded].cache_dir). Both locations are read by graded check and written by graded infer.
• Function names in the spec file use the module-qualified form: myapp.view, myapp/router.handle_request. Slashes for the module path, dot before the function name (same convention as external effects). Cache files continue to use bare names because each one is implicitly scoped to a module by its file location.
• Type field annotations gained the same qualification: type myapp.Handler.on_click : [Dom]. The bare form (type Handler.on_click : [Dom]) remains valid in cache files.
• Library authors who want their effect annotations to ship to consumers must add their spec file to included_files in gleam.toml. Without this, downstream packages will not see the library’s effects (and will fall back to [Unknown] for its functions, unless the catalog covers them).
• No automatic migration from the old layout. To migrate an existing project: move every effects/check/external/type line out of priv/graded/<module>.graded into <package_name>.graded at the project root, prefixing each function name with its module path. Then run graded infer and delete the old priv/graded/ directory.

[0.3.0] - 2026-04-07

Added

• Cross-module effect propagation: inferred effects from sibling project modules are used when analyzing other modules in the same project. Two-pass inference resolves inter-module dependencies.

[0.2.0] - 2026-04-07

Added

• Catalog entry for gleam_time (all modules pure; system_time, local_offset, utc_offset marked [Time]).
• Catalog entry for houdini (fully pure).
• Automatic effect inference for path dependencies declared in gleam.toml. Functions from local path deps are now inferred from source instead of being marked [Unknown].
• Path dependency inference loads existing .graded files for parameter bounds, improving accuracy for higher-order functions.
• Two-pass inference for path dependencies so cross-dep calls resolve correctly.

Fixed

• Record constructors (Ok, Error, Some, custom types) no longer inferred as [Unknown]. Gleam constructors start with an uppercase letter and are always pure.

[0.1.0] - 2025-04-04

Added

• Effect checker for Gleam via sidecar .graded annotation files.
• graded check command to enforce check annotations.
• graded infer command to infer and write effects annotations.
• graded format command with --check and --stdin modes.
• Higher-order effect tracking with parameter bounds.
• Field call effect tracking with type-aware resolution.
• External effect declarations for third-party functions.
• Wildcard effect [_] as the universal top element.
• Warnings for function references passed as values with known effects.
• Versioned catalog system resolved against manifest.toml.
• Catalog entries for gleam_stdlib, gleam_erlang, gleam_otp, gleam_http, gleam_httpc, gleam_json, gleam_regexp, gleam_yielder, gleam_crypto, lustre, lustre_http, simplifile, filepath, tom.