forst-lang / forst

60%

main: 76%

LAST BUILD ON BRANCH control-flow-narrowing

branch: control-flow-narrowing

CHANGE BRANCH

x

Reset

• control-flow-narrowing
• builtins-generics
• document-builtins-hover
• error-types
• expand-lsp-functionality
• feat/full-request-sidecar
• feat/map-read-result
• feat/sidecar-layer-hardening
• feat/type-unions-intersections
• fix-handle-value-constraints-in-field-lookup
• forst-cli-package
• generator-ts
• go-interop
• gofmt-examples-out
• improve-lexer
• increase-coverage-20260403
• increase-coverage-20260405
• lint-fix
• lsp
• lsp-navigate
• main
• refactor-transformer
• release
• result-types
• rfc-guard
• shape-guards
• showcase-example-tictactoe
• sidecar
• sidecar-release
• test-hash
• type-guards
• update-dependencies-20260402
• use-task
• vscode-lsp-extension

Build # 24014676417

Build Type

Pull #55

github

Committed by haveyaseen

Commit Message

feat(typechecker): flow merge, typeops, and predicate-chain hover

Add flow-local facts and join narrowings after if/else ladders so merged
types match control-flow merge points. Introduce typeops (Meet/Join) to
support that join logic and keep narrowing display consistent.

Unify variable hover: stack leading guard docs above a fenced type line,
using dotted predicate chains (FormatVariableOccurrenceTypeForHover and
PredicateChainForVariableHover). Stamp ensure subjects before applying
this line’s successor narrowing so hover reflects only prior ensures.

Document semantics in SEMANTICS_NARROWING.md; extend parser ensure spans
and add tests across narrow merge, typeops, LSP, and display.

Ignore local Go toolchain dirs under forst/.gocache and forst/.gotmp.

Example:

```forst
is (x: String) G {
	ensure x is Min(1)
	ensure x is Max(10)
}
```

Hover on the subject `x` on the second line shows `String.Min(1)` (not
`Max(10)` yet); later uses see the full merged chain.

Pull Request Pull Request #55: feat(typechecker): flow merge, typeops, and predicate-chain hover

Coverage Stats

388 of 541 new or added lines in 15 files covered. (71.72%)

9 existing lines in 4 files now uncovered.

14365 of 23818 relevant lines covered (60.31%)

13.91 hits per line