For design, see PistonDevelopers#636

- Added “typechk/refinement.dyon”
- Added “typechk/refinement_2.dyon”

- Added “typechk/refinement_3.dyon”

- Added “typechk/refinement_4.dyon”

- Removed `Type::is_concrete`
- Added “typechk/refinement_5.dyon”

- Fixed bug `a.goes_with(b)` => `b.goes_with(a)`
- Added “typechk/refinement_6.dyon”
- Added “typechk/refinement_7.dyon”

Closes PistonDevelopers#639

- Swap order of `Type::ambiguous`
- Added “typechk/refinement_8.dyon”
- Added “typechk/refinement_9.dyon”

- Added “typechk/refinement_10.dyon”
- Added “typechk/refinement_11.dyon”

- Added “typechk/refinement_12.dyon”
- Added “typechk/refinement_13.dyon”

- Added “typechk/refinement_14.dyon”
- Added “typechk/refinement_15.dyon”

- Added “typechk/refinement_16.dyon”
- Added “typechk/refinement_17.dyon”

- Added “typechk/refinement_18.dyon”
- Added “typechk/refinement_19.dyon”

- Added “typechk/refinement_20.dyon”
- Added “typechk/refinement_21.dyon”

- Added “typechk/refinement_22.dyon”
- Added “typechk/refinement_23.dyon”

- Added “syntax/secret_fail.dyon”

… something

- Added “typechk/void_refinement.dyon”

- Added “typechk/args_refinement.dyon”

- Added “typechk/refine_type_fail.dyon”

- Added “typechk/refinement_24.dyon”
- Added “typechk/refinement_25.dyon”

- Added ambiguity check for wrapper types
- Fixed doc comment on `Type::ambiguous`
- Added “typechk/refinement_26.dyon”
- Added “typechk/refinement_27.dyon”

- Added “typechk/refine_type_fail_2.dyon”

- Added “typechk/closure_ad_hoc.dyon”

- Added `UnOpEpression::into_expression`

- Added `Kind::Not`

- Removed `Expression::UnOp`
- Added `Node::rewrite_unop`
- Added `Kind::Neg`
- Removed `Kind::UnOp`
- Removed `Runtime::unop`

Closes PistonDevelopers#644

- Added “typechk/refine_closed_fail_1.dyon”
- Added “typechk/refine_closed_fail_2.dyon”
- Added “typechk/refine_closed_pass_1.dyon”

- Added efficient normalizing algorithm based on Group Theory

See PistonDevelopers#645

Use the semantics that none ad-hoc type is quantified over by `all`.

- Added `Type::all_ext`
- Added `Type::bind_ty_vars`
- Added `Type::insert_var`
- Added `Type::insert_none_var`
- Added `T` lazy static string
- Added some refine quantifier tests
- Updated `add` in “lib.dyon”
- Updated `add` extra type information
- Added support for type quantifier in syntax
- Push type variable names to “ty” node

See PistonDevelopers#640

- Use fake grab expressions to precompute lazy invariant values
- Added lazy invariant fake grap expressions
- Added lazy invariant `ok(_)` pattern
- Added lazy invariant `err(_)` pattern
- Added lazy invariant `some(_)` pattern
- Added test for lazy invariant
- Removed `Expression::BinOp`
- Added `ast::Lazy`
- Added `ast::Arg::lazy`
- Added `FnIndex::ExternalLazy`
- Removed `BinOpExpression::resolve_locals`
- Made `and_also` standard external function
- Made `or_else` standard external function
- Changed external function signature to return
`Result<Option<Variable>, String>`
- Returns value directly from external functions whenever possible
- Made `unwrap_or` lazy
- Use static pointers for external lazy invariants
- Added `LAZY_UNWRAP_OR`
- Added `LAZY_AND`
- Added `LAZY_OR`
- Added `LAZY_NO`
- Rewrite binary operators in type checker
- Delay errors in type checker for external functions
- Treat `Kind::Add`, `Kind::Mul`, `Kind::Pow` as expressions in type
checker
- Updated `dyon_fn!` macro to return value directly when possible
- Removed `Runtime::binop`
- Added ambiguity check for `sec[_] vs any`
- Added `standard_binop` to “write.rs”

- Fixed two warnings

- Added “typechk/arr_fail_2.dyon”

This case is covered by the type checker.

- Added `_` as printable character of objects