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experiment: make type system more nominal #711

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experiment: make type system more nominal #711

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2 changes: 1 addition & 1 deletion spec/declaration/record_spec.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -702,7 +702,7 @@ for i, name in ipairs({"records", "arrayrecords"}) do
end

function Foo.new(): Foo
return setmetatable({}, Foo) -- typing of arguments is being very permissive here, may change in the future and require a cast
return setmetatable({}, Foo as metatable<Foo>)
end

local foo = Foo.new()
Expand Down
22 changes: 13 additions & 9 deletions tl.lua
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Expand Up @@ -1418,7 +1418,7 @@ end

local function new_node(tokens, i, kind)
local t = tokens[i]
return { y = t.y, x = t.x, tk = t.tk, kind = kind or t.kind }
return { y = t.y, x = t.x, tk = t.tk, kind = kind or (t.kind) }
end

local function a_type(t)
Expand Down Expand Up @@ -7077,17 +7077,13 @@ tl.type_check = function(ast, opts)
end
return false, terr(t1, "cannot match against any alternatives of the polymorphic type")
elseif t1.typename == "nominal" and t2.typename == "nominal" then
local same, err = are_same_nominals(t1, t2)
if same then
return true
end
local t1r = resolve_tuple_and_nominal(t1)
local t2r = resolve_tuple_and_nominal(t2)
if is_record_type(t1r) and is_record_type(t2r) then
return same, err
else
if t1r.typename == "union" or t2r.typename == "union" then
return is_a(t1r, t2r, for_equality)
end

return are_same_nominals(t1, t2)
elseif t1.typename == "enum" and t2.typename == "string" then
local ok
if for_equality then
Expand Down Expand Up @@ -9088,7 +9084,7 @@ tl.type_check = function(ast, opts)
local infertype = infertypes[i]

local rt = resolve_tuple_and_nominal(t)
if rt.typename ~= "enum" and not same_type(t, infertype) then
if rt.typename ~= "enum" and (t.typename ~= "nominal" or rt.typename == "union") and not same_type(t, infertype) then
add_var(where, var.tk, infer_at(where, infertype), "const", "narrowed_declaration")
end
end
Expand Down Expand Up @@ -10064,6 +10060,14 @@ tl.type_check = function(ast, opts)
end
end

if orig_a.typename == "nominal" and orig_b.typename == "nominal" and not meta_on_operator then
if is_a(orig_a, orig_b) then
node.type = resolve_tuple(orig_a)
else
node_error(node, "cannot use operator '" .. node.op.op:gsub("%%", "%%%%") .. "' for distinct nominal types %s and %s", resolve_tuple(orig_a), resolve_tuple(orig_b))
end
end

if types_op == numeric_binop or node.op.op == ".." then
node.known = FACT_TRUTHY
end
Expand Down
22 changes: 13 additions & 9 deletions tl.tl
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Original file line number Diff line number Diff line change
Expand Up @@ -1418,7 +1418,7 @@ end

local function new_node(tokens: {Token}, i: integer, kind: NodeKind): Node
local t = tokens[i]
return { y = t.y, x = t.x, tk = t.tk, kind = kind or t.kind }
return { y = t.y, x = t.x, tk = t.tk, kind = kind or (t.kind as NodeKind) }
end

local function a_type(t: Type): Type
Expand Down Expand Up @@ -7077,17 +7077,13 @@ tl.type_check = function(ast: Node, opts: TypeCheckOptions): Result, string
end
return false, terr(t1, "cannot match against any alternatives of the polymorphic type")
elseif t1.typename == "nominal" and t2.typename == "nominal" then
local same, err = are_same_nominals(t1, t2)
if same then
return true
end
local t1r = resolve_tuple_and_nominal(t1)
local t2r = resolve_tuple_and_nominal(t2)
if is_record_type(t1r) and is_record_type(t2r) then
return same, err
else
if t1r.typename == "union" or t2r.typename == "union" then
return is_a(t1r, t2r, for_equality)
end

return are_same_nominals(t1, t2)
elseif t1.typename == "enum" and t2.typename == "string" then
local ok: boolean
if for_equality then
Expand Down Expand Up @@ -9088,7 +9084,7 @@ tl.type_check = function(ast: Node, opts: TypeCheckOptions): Result, string
local infertype = infertypes[i]

local rt = resolve_tuple_and_nominal(t)
if rt.typename ~= "enum" and not same_type(t, infertype) then
if rt.typename ~= "enum" and (t.typename ~= "nominal" or rt.typename == "union") and not same_type(t, infertype) then
add_var(where, var.tk, infer_at(where, infertype), "const", "narrowed_declaration")
end
end
Expand Down Expand Up @@ -10064,6 +10060,14 @@ tl.type_check = function(ast: Node, opts: TypeCheckOptions): Result, string
end
end

if orig_a.typename == "nominal" and orig_b.typename == "nominal" and not meta_on_operator then
if is_a(orig_a, orig_b) then
node.type = resolve_tuple(orig_a)
else
node_error(node, "cannot use operator '" .. node.op.op:gsub("%%", "%%%%") .. "' for distinct nominal types %s and %s", resolve_tuple(orig_a), resolve_tuple(orig_b))
end
end

if types_op == numeric_binop or node.op.op == ".." then
node.known = FACT_TRUTHY
end
Expand Down
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