Final test batch and associated fixes

anselme/ast/Closure.lua

@@ -38,6 +38,9 @@ Closure = Runtime(Overloadable) {
 	format_parameters = function(self, state)
 		return self.func.parameters:format(state)
 	end,
+	hash_parameters = function(self)
+		return self.func.parameters:hash()
+	end,
 	call_dispatched = function(self, state, args)
 		local calling_environment = state.scope:capture()
 		state.scope:push(self.scope)

anselme/ast/Function.lua

@@ -40,6 +40,9 @@ Function = Overloadable {
 	format_parameters = function(self, state)
 		return self.parameters:format(state)
 	end,
+	hash_parameters = function(self)
+		return self.parameters:hash()
+	end,
 	call_dispatched = function(self, state, args)
 		state.scope:push()
 		args:bind_parameter_tuple(state, self.parameters)

anselme/ast/List.lua

@@ -42,7 +42,7 @@ List = ast.abstract.Runtime {
 	end,
 
 	len = function(self, state)
-		return #self.branched:get(state).list
+		return self.branched:get(state):len()
 	end,
 	iter = function(self, state)
 		return ipairs(self.branched:get(state).list)

anselme/ast/LuaFunction.lua

@@ -20,6 +20,10 @@ LuaFunction = ast.abstract.Runtime(Overloadable) {
 		fn(self.parameters, ...)
 	end,
 
+	_hash = function(self)
+		return ("%s<%s;%s>"):format(self.type, self.parameters:hash(), tostring(self.func))
+	end,
+
 	_format = function(self, ...)
 		if self.parameters.assignment then
 			return "$"..self.parameters:format(...).."; <lua function>"
@@ -37,6 +41,9 @@ LuaFunction = ast.abstract.Runtime(Overloadable) {
 	format_parameters = function(self, state)
 		return self.parameters:format(state)
 	end,
+	hash_parameters = function(self)
+		return self.parameters:hash()
+	end,
 	call_dispatched = function(self, state, args)
 		local lua_args = { state }
 

anselme/ast/Overload.lua

@@ -1,17 +1,25 @@
 local ast = require("anselme.ast")
+local assert0 = require("anselme.common").assert0
 
 local Overload
 Overload = ast.abstract.Node {
 	type = "overload",
 	_evaluated = true,
 
-	list = nil,
+	list = nil, -- list of Overloadable
+	_signatures = nil, -- map {[parameter hash]=true} of call signatures already registered in this overload
 
 	init = function(self, ...)
-		self.list = { ... }
+		self.list = {}
+		self._signatures = {}
+		for _, fn in ipairs{...} do
+			self:insert(fn)
+		end
 	end,
 	insert = function(self, val) -- only for construction
+		assert0(not self._signatures[val:hash_parameters()], ("a function with parameters %s is already defined in the overload"):format(val:format_parameters()))
 		table.insert(self.list, val)
+		self._signatures[val:hash_parameters()] = true
 	end,
 
 	_format = function(self, ...)

anselme/ast/Tuple.lua

@@ -60,6 +60,9 @@ Tuple = ast.abstract.Node {
 		if index < 0 then index = #self.list + 1 + index end
 		if index > #self.list or index == 0 then error("tuple index out of bounds", 0) end
 		return self.list[index]
+	end,
+	len =  function(self)
+		return #self.list
 	end
 }
 

anselme/ast/abstract/Overloadable.lua

@@ -16,6 +16,10 @@ return ast.abstract.Node {
 	format_parameters = function(self, state)
 		return self:format(state)
 	end,
+	-- return string
+	hash_parameters = function(self)
+		return self:hash()
+	end,
 
 	-- can be called either after a successful :dispatch or :compatible_with_arguments
 	call_dispatched = function(self, state, args)

anselme/state/State.lua

@@ -12,6 +12,7 @@ local parser = require("anselme.parser")
 local binser = require("anselme.lib.binser")
 local assert0 = require("anselme.common").assert0
 local anselme
+local Identifier
 
 local State
 State = class {
@@ -90,6 +91,18 @@ State = class {
 	define_local = function(self, name, value, func, raw_mode)
 		self.scope:define_lua(name, value, func, raw_mode)
 	end,
+	--- Returns true if `name` (string) is defined in the global scope.
+	--- Returns false otherwise.
+	defined = function(self, name)
+		self.scope:push_global()
+		local r = self:defined_local(name)
+		self.scope:pop()
+		return r
+	end,
+	--- Same as `:defined`, but check if the variable is defined in the current scope.
+	defined_local = function(self, name)
+		return self.scope:defined(Identifier:new(name))
+	end,
 
 	--- For anything more advanced, you can directly access the current scope stack stored in `state.scope`.
 	-- See [state/ScopeStack.lua](../state/ScopeStack.lua) for details; the documentation is not as polished as this file but you should still be able to find your way around.
@@ -160,7 +173,7 @@ State = class {
 			self.scope:reset()
 			type, data = "error", type
 		end
-		if coroutine.status(self._coroutine) == "dead" then
+		if self._coroutine and coroutine.status(self._coroutine) == "dead" then
 			self._coroutine = nil
 		end
 		return type, data
@@ -171,8 +184,11 @@ State = class {
 	--
 	-- If `code` is given, the script will not be disabled but instead will be immediately replaced with this new script.
 	-- The new script will then be started on the next `:step` and will preserve the current scope. This can be used to trigger an exit function or similar in the active script.
+	--
+	-- If this is called from within a running script, this will raise an `interrupt` event in order to stop the current script execution.
 	interrupt = function(self, code, source)
 		assert(self:active(), "trying to interrupt but no script is currently active")
+		local called_from_script = self:state() == "running"
 		if code then
 			self._coroutine = coroutine.create(function()
 				local r = assert0(self:eval_local(code, source))
@@ -184,6 +200,7 @@ State = class {
 			self.scope:reset()
 			self._coroutine = nil
 		end
+		if called_from_script then coroutine.yield("interrupt") end
 	end,
 
 	--- Evaluate an expression in the global scope.
@@ -221,5 +238,7 @@ State = class {
 
 package.loaded[...] = State
 anselme = require("anselme")
+local ast = require("anselme.ast")
+Identifier = ast.Identifier
 
 return State

anselme/stdlib/checkpoint.lua

@@ -1,5 +1,5 @@
 local ast = require("anselme.ast")
-local ArgumentTuple, Boolean = ast.ArgumentTuple, ast.Boolean
+local ArgumentTuple, Boolean, Nil = ast.ArgumentTuple, ast.Boolean, ast.Nil
 
 local resume_manager = require("anselme.state.resume_manager")
 
@@ -47,4 +47,11 @@ return {
 			return resume_manager:get(state)
 		end
 	},
+	{
+		"merge branch", "()",
+		function(state)
+			state:merge()
+			return Nil:new()
+		end
+	}
 }

anselme/stdlib/number.lua

@@ -46,4 +46,8 @@ return {
 	{ "_%_", "(a::number, b::number)", function(state, a, b) return Number:new(a.number % b.number) end },
 	{ "_^_", "(a::number, b::number)", function(state, a, b) return Number:new(a.number ^ b.number) end },
 	{ "-_", "(a::number)", function(state, a) return Number:new(-a.number) end },
+
+	{ "rand", "(min::number, max::number)", function(state, min, max) return Number:new(math.random(min.number, max.number)) end },
+	{ "rand", "(max::number)", function(state, max) return Number:new(math.random(max.number)) end },
+	{ "rand", "()", function(state) return Number:new(math.random()) end },
 }

anselme/stdlib/script_script.lua

@@ -1,31 +1,34 @@
 return [[
 :@script = $(name, fn)
-	:&current checkpoint => "{name}.checkpoint"!persist(false)
+	fn.:&current checkpoint => "{name}.checkpoint"!persist(false)
-	:&reached => "{name}.reached"!persist(*{})
+	fn.:&reached => "{name}.reached"!persist(*{})
+	fn.:&run => "{name}.run"!persist(0)
+
 	:resumed from = ()
 
 	fn.:check = $(anchor::anchor)
-		reached(anchor) = (reached(anchor) | 0) + 1
+		fn.reached(anchor) = (fn.reached(anchor) | 0) + 1
 	fn.:checkpoint = $(anchor::anchor)
-		current checkpoint = anchor
+		fn.current checkpoint = anchor
 		resumed from != anchor ~
-			reached(anchor) = (reached(anchor) | 0) + 1
+			fn.reached(anchor) = (fn.reached(anchor) | 0) + 1
+			merge branch!
 	fn.:checkpoint = $(anchor::anchor, on resume::function)
-		current checkpoint = anchor
+		fn.current checkpoint = anchor
 		resumed from == anchor | resuming(1) ~
 			on resume!
 		~
-			reached(anchor) = (reached(anchor) | 0) + 1
+			fn.reached(anchor) = (fn.reached(anchor) | 0) + 1
+			merge branch!
 
 	:f = $
-		current checkpoint ~
+		fn.current checkpoint ~
-			resumed from = current checkpoint
+			resumed from = fn.current checkpoint
-			fn!resume(current checkpoint)
+			fn!resume(fn.current checkpoint)
 		~
 			resumed from = ()
 			fn!
-		run += 1
+		fn.run += 1
-	f.:&run => "{name}.run"!persist(0)
 
 	f!type("script")
 
@@ -35,18 +38,11 @@ return [[
 	s!value!
 
 :@$_._(s::is script, k::string)
-	:v = s!value
+	@(s!value).fn.(k)
-	v.fn!has upvalue(k) ~
-		@v.fn.(k)
-	~
-		@v.(k)
-
 :@$_._(s::is script, k::string) = val
-	:v = s!value
+	(s!value).fn.(k) = val
-	v.fn!has upvalue(k) ~
+:@$_._(s::is script, k::symbol) = val
-		v.fn.(k) = val
+	(s!value).fn.(k) = val
-	~
-		v.(k) = val
 
 :@$from(s::is script, a::anchor)
 	s.current checkpoint = a
@@ -54,4 +50,24 @@ return [[
 :@$from(s::is script)
 	s.current checkpoint = ()
 	@s!
+
+((Additionnal helpers))
+:@$ cycle(l::tuple)
+	:i = 2
+	i <= l!len ~?
+		l(i).run < l(1).run ~
+			@l(i)!
+		i += 1
+	l(1)!
+
+:@$ next(l::tuple)
+	:i = 1
+	i <= l!len ~?
+		l(i).run == 0 ~
+			@l(i)!
+		i += 1
+	l(i-1)!
+
+:@$ random(l::tuple)
+	l(rand(1, l!len))!
 ]]

anselme/stdlib/structures.lua

@@ -15,6 +15,12 @@ return {
 			return l:get(i.number)
 		end
 	},
+	{
+		"len", "(l::tuple)",
+		function(state, l)
+			return Number:new(l:len())
+		end
+	},
 
 	-- list
 	{

test/results/checkpoint merging mutable value.ans

@@ -0,0 +1,20 @@
+--# run #--
+--- text ---
+| {}"1,2: " {}"*[1, 2]" {}"" |
+--- text ---
+| {}"1,2,3: " {}"*[1, 2, 3]" {}"" |
+--- text ---
+| {}"1,2,3,4: " {}"*[1, 2, 3, 4]" {}"" |
+--- text ---
+| {}"1,2,3,4,5: " {}"*[1, 2, 3, 4, 5]" {}"" |
+--- error ---
+cancel merge
+	↳ from test/tests/checkpoint merging mutable value.ans:24:6 in call: error("cancel merge")
+	↳ from ? in block: :l = *[1, 2]…
+--# post run check #--
+--- text ---
+| {}"1,2,3,4: " {}"*[1, 2, 3, 4]" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/checkpoint merging variable.ans

@@ -0,0 +1,20 @@
+--# run #--
+--- text ---
+| {}"1: " {}"1" {}"" |
+--- text ---
+| {}"2: " {}"2" {}"" |
+--- text ---
+| {}"3: " {}"3" {}"" |
+--- text ---
+| {}"4: " {}"4" {}"" |
+--- error ---
+cancel merge
+	↳ from test/tests/checkpoint merging variable.ans:24:6 in call: error("cancel merge")
+	↳ from ? in block: :l = 1…
+--# post run check #--
+--- text ---
+| {}"3: " {}"3" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/commit.ans

@@ -0,0 +1,21 @@
+--# run #--
+--- text ---
+| {}"before: " {}"2" {}"" |
+--# parallel script #--
+--- text ---
+| {}"parallel: " {}"5" {}"" |
+--- return ---
+()
+--# main script #--
+--- text ---
+| {}"after: " {}"2" {}"" |
+--# parallel script #--
+--- text ---
+| {}"parallel: " {}"2" {}"" |
+--- return ---
+()
+--# main script #--
+--- return ---
+()
+--# saved #--
+{"bar.checkpoint":#foo, "bar.reached":*{#foo:1}, "bar.run":1}

test/results/custom event.ans

@@ -0,0 +1,10 @@
+--# run #--
+--- wait ---
+5
+--- text ---
+| {}"ah" |
+| {}"ho" |
+--- return ---
+()
+--# saved #--
+{}

test/results/exported variable nested.ans

@@ -5,7 +5,7 @@
 --- text ---
 | {}"" {}"42" {}"" |
 --- error ---
-identifier "z" is undefined in branch 6843ee85-cea8-445d-10f21-9a8e54372094
+identifier "z" is undefined in branch 1228bcf1-5118-4955-10048-8fda790007be
 	↳ from test/tests/exported variable nested.ans:12:3 in identifier: z
 	↳ from test/tests/exported variable nested.ans:12:1 in text interpolation: | {z} |
 	↳ from test/tests/exported variable nested.ans:12:1 in translatable: | {z} |

test/results/function conflict.ans

@@ -0,0 +1,7 @@
+--# run #--
+--- error ---
+a function with parameters (a, b) is already defined in the overload
+	↳ from test/tests/function conflict.ans:5:1 in definition: :f = ($(a, b) 0)
+	↳ from ? in block: :f = ($(a, b) 0)…
+--# saved #--
+{}

test/results/function cycle.ans

@@ -0,0 +1,15 @@
+--# run #--
+--- text ---
+| {}"a" |
+--- text ---
+| {}"b" |
+--- text ---
+| {}"c" |
+--- text ---
+| {}"a" |
+--- text ---
+| {}"b" |
+--- return ---
+()
+--# saved #--
+{"a.checkpoint":false, "a.run":2, "b.checkpoint":false, "b.run":2, "c.checkpoint":false, "c.run":1}

test/results/function next.ans

@@ -0,0 +1,15 @@
+--# run #--
+--- text ---
+| {}"a" |
+--- text ---
+| {}"b" |
+--- text ---
+| {}"c" |
+--- text ---
+| {}"c" |
+--- text ---
+| {}"c" |
+--- return ---
+()
+--# saved #--
+{"a.checkpoint":false, "a.run":1, "b.checkpoint":false, "b.run":1, "c.checkpoint":false, "c.run":3}

test/results/function random.ans

@@ -0,0 +1,15 @@
+--# run #--
+--- text ---
+| {}"c" |
+--- text ---
+| {}"a" |
+--- text ---
+| {}"c" |
+--- text ---
+| {}"a" |
+--- text ---
+| {}"b" |
+--- return ---
+()
+--# saved #--
+{"a.checkpoint":false, "a.run":2, "b.checkpoint":false, "b.run":1, "c.checkpoint":false, "c.run":2}

test/results/function scope wrong.ans

@@ -1,6 +1,6 @@
 --# run #--
 --- error ---
-identifier "b" is undefined in branch 0a138a38-3faa-4478-10f6f-1a9de1e0a8e1
+identifier "b" is undefined in branch 57b4c67d-b128-4b9a-11e39-0e6612f1210e
 	↳ from test/tests/function scope wrong.ans:4:7 in identifier: b
 	↳ from test/tests/function scope wrong.ans:4:1 in text interpolation: | a: {b} |
 	↳ from test/tests/function scope wrong.ans:4:1 in translatable: | a: {b} |

test/results/function separate variable from variants.ans

@@ -1,6 +1,7 @@
 --# run #--
 --- error ---
-can't call overload overload<($(s::($(x) type(x) == t), k::($(x) <lua function>)) = val; _), ($(s::($(x) type(x) == t), k::($(x) <lua function>)) _), ($(c::($(x) <lua function>), s::($(x) <lua function>)) = v; <lua function>), ($(c::($(x) <lua function>), s::($(x) <lua function>)) = v; <lua function>), ($(c::($(x) <lua function>), s::($(x) <lua function>)) <lua function>)>: no function match (overload<($(b) _), ($(x) _), ($() _)>, "a"), possible functions were:
+can't call overload overload<($(s::($(x) type(x) == t), k::($(x) <lua function>)) = val; _), ($(s::($(x) type(x) == t), k::($(x) <lua function>)) = val; _), ($(s::($(x) type(x) == t), k::($(x) <lua function>)) _), ($(c::($(x) <lua function>), s::($(x) <lua function>)) = v; <lua function>), ($(c::($(x) <lua function>), s::($(x) <lua function>)) = v; <lua function>), ($(c::($(x) <lua function>), s::($(x) <lua function>)) <lua function>)>: no function match (overload<($(b) _), ($(x) _), ($() _)>, "a"), possible functions were:
+	• (s::($(x) type(x) == t), k::($(x) <lua function>)) = val: expected 3 arguments, received 2
 	• (s::($(x) type(x) == t), k::($(x) <lua function>)) = val: expected 3 arguments, received 2
 	• (s::($(x) type(x) == t), k::($(x) <lua function>)): type check failure for parameter s in function (s::($(x) type(x) == t), k::($(x) <lua function>))
 	• (c::($(x) <lua function>), s::($(x) <lua function>)) = v: expected 3 arguments, received 2

test/results/interrupt callback nested paragraph.ans

@@ -0,0 +1,11 @@
+--# run #--
+--- text ---
+| {}"before: " {}"2" {}"" |
+--- interrupt ---
+nil
+--- text ---
+| {}"in interrupt: " {}"2" {}"" |
+--- return ---
+()
+--# saved #--
+{"bar.checkpoint":false}

test/results/interrupt callback nested.ans

@@ -0,0 +1,11 @@
+--# run #--
+--- text ---
+| {}"before: " {}"2" {}"" |
+--- interrupt ---
+nil
+--- text ---
+| {}"in interrupt: " {}"2" {}"" |
+--- return ---
+()
+--# saved #--
+{"bar.checkpoint":false}

test/results/interrupt callback.ans

@@ -0,0 +1,11 @@
+--# run #--
+--- text ---
+| {}"before: " {}"2" {}"" |
+--- interrupt ---
+nil
+--- text ---
+| {}"in interrupt: " {}"2" {}"" |
+--- return ---
+()
+--# saved #--
+{"bar.checkpoint":false}

test/results/interrupt no callback.ans

@@ -0,0 +1,7 @@
+--# run #--
+--- text ---
+| {}"before: " {}"2" {}"" |
+--- interrupt ---
+nil
+--# saved #--
+{}

test/results/map index accross checkpoints.ans

@@ -0,0 +1,19 @@
+--# run #--
+--- text ---
+| {}"x=" {}"*{1:4}" {}"" |
+--- text ---
+| {}"1=" {}"true" {}"" |
+--- text ---
+| {}"a(x)=" {}"4" {}"" |
+--- text ---
+| {}"a(x)=" {}"4" {}"" |
+--- text ---
+| {}"a(x)=" {}"4" {}"" |
+--- text ---
+| {}"a(x)=" {}"4" {}"" |
+--- text ---
+| {}"no=" {}"()" {}"" |
+--- return ---
+()
+--# saved #--
+{"f.checkpoint":#ch c, "f.reached":*{#ch a:1, #ch b:1, #ch c:1}, "f.run":1}

test/results/merge nested mutable bis.ans

@@ -0,0 +1,10 @@
+--# run #--
+--- return ---
+()
+--# post run check #--
+--- text ---
+| {}"[1,[2,3,4]]: " {}"*[1, *[2, 3, 4]]" {}"" |
+--- return ---
+()
+--# saved #--
+{"f.checkpoint":#d, "f.reached":*{#c:1, #d:1}, "f.run":1}

test/results/merge nested mutable error bis.ans

@@ -0,0 +1,31 @@
+--# run #--
+--- error ---
+abort
+	↳ from test/tests/merge nested mutable error bis.ans:14:7 in call: error("abort")
+	↳ from test/tests/merge nested mutable error bis.ans:3:1 in block: insert(a, b)…
+	↳ from test/tests/merge nested mutable error bis.ans:3:18 in call: _
+	↳ from test/tests/merge nested mutable error bis.ans:3:17 in return boundary: _
+	↳ from test/tests/merge nested mutable error bis.ans:3:17 in return boundary: _
+	↳ from script.ans:29:6 in call: fn!
+	↳ from script.ans:27:3 in block: resumed from = ()…
+	↳ from script.ans:27:5 in call: _
+	↳ from script.ans:27:3 in call: ~_
+	↳ from script.ans:27:3 in partial scope: ~_…
+	↳ from script.ans:23:2 in block: fn . "current checkpoint" ~…
+	↳ from script.ans:23:9 in call: _
+	↳ from script.ans:23:7 in return boundary: _
+	↳ from script.ans:23:7 in return boundary: _
+	↳ from script.ans:37:9 in call: value(s)!
+	↳ from script.ans:36:1 in block: value(s)!
+	↳ from script.ans:36:20 in call: _
+	↳ from script.ans:36:1 in return boundary: _
+	↳ from script.ans:36:1 in return boundary: _
+	↳ from test/tests/merge nested mutable error bis.ans:19:2 in call: f!
+	↳ from ? in block: :a = *[1]…
+--# post run check #--
+--- text ---
+| {}"[1,[2,3]]: " {}"*[1, *[2, 3]]" {}"" |
+--- return ---
+()
+--# saved #--
+{"f.checkpoint":#d, "f.reached":*{#c:1, #d:1}}

test/results/merge nested mutable error.ans

@@ -0,0 +1,31 @@
+--# run #--
+--- error ---
+abort
+	↳ from test/tests/merge nested mutable error.ans:14:7 in call: error("abort")
+	↳ from test/tests/merge nested mutable error.ans:3:1 in block: insert(a, b)…
+	↳ from test/tests/merge nested mutable error.ans:3:18 in call: _
+	↳ from test/tests/merge nested mutable error.ans:3:17 in return boundary: _
+	↳ from test/tests/merge nested mutable error.ans:3:17 in return boundary: _
+	↳ from script.ans:29:6 in call: fn!
+	↳ from script.ans:27:3 in block: resumed from = ()…
+	↳ from script.ans:27:5 in call: _
+	↳ from script.ans:27:3 in call: ~_
+	↳ from script.ans:27:3 in partial scope: ~_…
+	↳ from script.ans:23:2 in block: fn . "current checkpoint" ~…
+	↳ from script.ans:23:9 in call: _
+	↳ from script.ans:23:7 in return boundary: _
+	↳ from script.ans:23:7 in return boundary: _
+	↳ from script.ans:37:9 in call: value(s)!
+	↳ from script.ans:36:1 in block: value(s)!
+	↳ from script.ans:36:20 in call: _
+	↳ from script.ans:36:1 in return boundary: _
+	↳ from script.ans:36:1 in return boundary: _
+	↳ from test/tests/merge nested mutable error.ans:19:2 in call: f!
+	↳ from ? in block: :a = *[1]…
+--# post run check #--
+--- text ---
+| {}"[1,[2,3]]: " {}"*[1, *[2, 3]]" {}"" |
+--- return ---
+()
+--# saved #--
+{"f.checkpoint":#d, "f.reached":*{#c:1, #d:1}}

test/results/merge nested mutable.ans

@@ -0,0 +1,10 @@
+--# run #--
+--- return ---
+()
+--# post run check #--
+--- text ---
+| {}"[1,[2,3],4]: " {}"*[1, *[2, 3], 4]" {}"" |
+--- return ---
+()
+--# saved #--
+{"f.checkpoint":#d, "f.reached":*{#c:1, #d:1}, "f.run":1}

test/results/scope checkpoint mutable bis error.ans

@@ -0,0 +1,42 @@
+--# run #--
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3]" {}" " {}"*[1, *[99], 3]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"REC" |
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3, 4]" {}" " {}"*[1, *[99], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"f2: " {}"*[1, *[99], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK 2" |
+--- error ---
+t
+	↳ from test/tests/scope checkpoint mutable bis error.ans:32:7 in call: error("t")
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:1 in block: insert(t, len(l) + 1)…
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:8 in call: _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:19:4 in call: f(t)
+	↳ from test/tests/scope checkpoint mutable bis error.ans:15:2 in block: | REC |…
+	↳ from test/tests/scope checkpoint mutable bis error.ans:15:10 in call: _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:15:8 in call: n < 1 ~ _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:15:2 in partial scope: n < 1 ~…
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:1 in block: insert(t, len(l) + 1)…
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:8 in call: _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable bis error.ans:41:2 in call: f(l)
+	↳ from ? in block: :x = *[99]…
+--# post run check #--
+--- text ---
+| {}"AFTER ERROR" |
+--- text ---
+| {}"l: " {}"*[1, *[99], 3, 4]" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/scope checkpoint mutable bis.ans

@@ -0,0 +1,35 @@
+--# run #--
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3]" {}" " {}"*[1, *[99], 3]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"REC" |
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3, 4]" {}" " {}"*[1, *[99], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"f2: " {}"*[1, *[99], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK 2" |
+--- text ---
+| {}"f3: " {}"*[1, *[99, 6], 3, 4, 5]" {}" " {}"*[1, *[99, 6], 3, 4, 5]" {}"" |
+--- text ---
+| {}"END REC" |
+--- text ---
+| {}"f2: " {}"*[1, *[99, 6], 3, 4, 5]" {}"" |
+--- text ---
+| {}"CHECK 2" |
+--- text ---
+| {}"f3: " {}"*[1, *[99, 6, 7], 3, 4, 5, 6]" {}" " {}"*[1, *[99, 6, 7], 3, 4, 5, 6]" {}"" |
+--- text ---
+| {}"FINAL" |
+--- text ---
+| {}"l: " {}"*[1, *[99, 6, 7], 3, 4, 5, 6]" {}"" |
+--- text ---
+| {}"x: " {}"*[99, 6, 7]" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/scope checkpoint mutable error.ans

@@ -0,0 +1,38 @@
+--# run #--
+--- text ---
+| {}"f1: " {}"*[1, 2]" {}" " {}"*[1, 2]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"REC" |
+--- text ---
+| {}"f1: " {}"*[1, 2, 3]" {}" " {}"*[1, 2, 3]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- error ---
+t
+	↳ from test/tests/scope checkpoint mutable error.ans:23:7 in call: error("t")
+	↳ from test/tests/scope checkpoint mutable error.ans:5:1 in block: insert(t, len(l) + 1)…
+	↳ from test/tests/scope checkpoint mutable error.ans:5:8 in call: _
+	↳ from test/tests/scope checkpoint mutable error.ans:5:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable error.ans:5:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable error.ans:17:4 in call: f(t)
+	↳ from test/tests/scope checkpoint mutable error.ans:13:2 in block: | REC |…
+	↳ from test/tests/scope checkpoint mutable error.ans:13:10 in call: _
+	↳ from test/tests/scope checkpoint mutable error.ans:13:8 in call: n < 1 ~ _
+	↳ from test/tests/scope checkpoint mutable error.ans:13:2 in partial scope: n < 1 ~…
+	↳ from test/tests/scope checkpoint mutable error.ans:5:1 in block: insert(t, len(l) + 1)…
+	↳ from test/tests/scope checkpoint mutable error.ans:5:8 in call: _
+	↳ from test/tests/scope checkpoint mutable error.ans:5:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable error.ans:5:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable error.ans:32:2 in call: f(l)
+	↳ from ? in block: :l = *[1]…
+--# post run check #--
+--- text ---
+| {}"AFTER ERROR" |
+--- text ---
+| {}"l: " {}"*[1, 2, 3]" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/scope checkpoint mutable ter error.ans

@@ -0,0 +1,42 @@
+--# run #--
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3]" {}" " {}"*[1, *[99], 3]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"REC" |
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3, 4]" {}" " {}"*[1, *[99], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"f2: " {}"*[1, *[99, 12], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK 2" |
+--- error ---
+t
+	↳ from test/tests/scope checkpoint mutable ter error.ans:34:7 in call: error("t")
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:1 in block: insert(t, len(l) + 1)…
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:8 in call: _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:19:4 in call: f(t)
+	↳ from test/tests/scope checkpoint mutable ter error.ans:15:2 in block: | REC |…
+	↳ from test/tests/scope checkpoint mutable ter error.ans:15:10 in call: _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:15:8 in call: n < 1 ~ _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:15:2 in partial scope: n < 1 ~…
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:1 in block: insert(t, len(l) + 1)…
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:8 in call: _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:7:1 in return boundary: _
+	↳ from test/tests/scope checkpoint mutable ter error.ans:43:2 in call: f(l)
+	↳ from ? in block: :x = *[99]…
+--# post run check #--
+--- text ---
+| {}"AFTER ERROR" |
+--- text ---
+| {}"l: " {}"*[1, *[99, 12], 3, 4]" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/scope checkpoint mutable ter.ans

@@ -0,0 +1,35 @@
+--# run #--
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3]" {}" " {}"*[1, *[99], 3]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"REC" |
+--- text ---
+| {}"f1: " {}"*[1, *[99], 3, 4]" {}" " {}"*[1, *[99], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"f2: " {}"*[1, *[99, 12], 3, 4]" {}"" |
+--- text ---
+| {}"CHECK 2" |
+--- text ---
+| {}"f3: " {}"*[1, *[99, 12, 6], 3, 4, 5]" {}" " {}"*[1, *[99, 12, 6], 3, 4, 5]" {}"" |
+--- text ---
+| {}"END REC" |
+--- text ---
+| {}"f2: " {}"*[1, *[99, 12, 6, 12], 3, 4, 5]" {}"" |
+--- text ---
+| {}"CHECK 2" |
+--- text ---
+| {}"f3: " {}"*[1, *[99, 12, 6, 12, 7], 3, 4, 5, 6]" {}" " {}"*[1, *[99, 12, 6, 12, 7], 3, 4, 5, 6]" {}"" |
+--- text ---
+| {}"FINAL" |
+--- text ---
+| {}"l: " {}"*[1, *[99, 12, 6, 12, 7], 3, 4, 5, 6]" {}"" |
+--- text ---
+| {}"x: " {}"*[99, 12, 6, 12, 7]" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/scope checkpoint mutable.ans

@@ -0,0 +1,25 @@
+--# run #--
+--- text ---
+| {}"f1: " {}"*[1, 2]" {}" " {}"*[1, 2]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"REC" |
+--- text ---
+| {}"f1: " {}"*[1, 2, 3]" {}" " {}"*[1, 2, 3]" {}"" |
+--- text ---
+| {}"CHECK" |
+--- text ---
+| {}"f2: " {}"*[1, 2, 3, 4]" {}"" |
+--- text ---
+| {}"END REC" |
+--- text ---
+| {}"f2: " {}"*[1, 2, 3, 4, 5]" {}"" |
+--- text ---
+| {}"FINAL" |
+--- text ---
+| {}"l: " {}"*[1, 2, 3, 4, 5]" {}"" |
+--- return ---
+()
+--# saved #--
+{}

test/results/seen checkpoint resume.ans

@@ -0,0 +1,11 @@
+--# run #--
+--- text ---
+| {}"a: " {}"0" {}"" |
+--- text ---
+| {}"a: " {}"1" {}"" |
+--- text ---
+| {}"a: " {}"2" {}"" |
+--- return ---
+()
+--# saved #--
+{"fn.checkpoint":#a, "fn.run":3}

test/results/unseen line.ans

@@ -0,0 +1,11 @@
+--# run #--
+--- text ---
+| {}"a" |
+| {}"seen only once" |
+| {}"b" |
+| {}"a" |
+| {}"b" |
+--- return ---
+()
+--# saved #--
+{"x.checkpoint":false, "x.run":2}

test/run.lua

@@ -5,6 +5,7 @@ local lfs = require("lfs")
 package.path = "./?/init.lua;./?.lua;" .. package.path
 local anselme = require("anselme")
 local persistent_manager = require("anselme.state.persistent_manager")
+local ast = require("anselme.ast")
 
 -- simple random to get the same result across lua versions
 local prev = 0
@@ -22,25 +23,7 @@ function math.random(a, b)
 	end
 end
 
--- run a test file and return the result
+local function run_loop(run_state, out)
-local function run(path)
-	local state = anselme:new()
-	state:load_stdlib()
-
-	local run_state = state:branch()
-
-	local f = assert(io.open(path, "r"))
-	local s, block = pcall(anselme.parse, f:read("*a"), path)
-	f:close()
-
-	if not s then
-		return "--# parse error #--\n"..tostring(block)
-	end
-
-	run_state:run(block)
-
-	local out = { "--# run #--" }
-
 	while run_state:active() do
 		local e, data = run_state:step()
 		table.insert(out, "--- "..e.." ---")
@@ -65,9 +48,51 @@ local function run(path)
 			table.insert(out, tostring(data))
 		end
 	end
+end
+
+-- run a test file and return the result
+local function run(path)
+	local out = { "--# run #--" }
+
+	local state = anselme:new()
+	state:load_stdlib()
+
+	state:define("error", "(message=\"error\")", function(message) error(message, 0) end)
+	state:define("interrupt", "(code::string)", function(state, code) state:interrupt(code:to_lua(state), "interrupt") return ast.Nil:new() end, true)
+	state:define("interrupt", "()", function(state) state:interrupt() return ast.Nil:new() end, true)
+	state:define("wait", "(duration::number)", function(duration) coroutine.yield("wait", duration) end)
+	state:define("run in new branch", "(code)", function(code)
+		local parallel_state = state:branch()
+		table.insert(out, "--# parallel script #--")
+		parallel_state:run(code, "parallel")
+		run_loop(parallel_state, out)
+		table.insert(out, "--# main script #--")
+	end)
+
+	local run_state = state:branch()
+
+	local f = assert(io.open(path, "r"))
+	local s, block = pcall(anselme.parse, f:read("*a"), path)
+	f:close()
+
+	if not s then
+		return "--# parse error #--\n"..tostring(block)
+	end
+
+	run_state:run(block)
+
+	run_loop(run_state, out)
+
+	if state:defined("post run check") then
+		local post_run_state = state:branch()
+		post_run_state:run("post run check!")
+
+		table.insert(out, "--# post run check #--")
+		run_loop(post_run_state, out)
+	end
 
 	table.insert(out, "--# saved #--")
-	table.insert(out, persistent_manager:capture(run_state):format(run_state))
+	table.insert(out, persistent_manager:capture(state):format(state))
 
 	return table.concat(out, "\n")
 end

test/tests/checkpoint merging mutable value.ans

@@ -0,0 +1,24 @@
+:l = *[1,2]
+
+:@$ post run check
+	|1,2,3,4: {l}
+
+|1,2: {l}
+
+l!insert(3)
+
+|1,2,3: {l}
+
+merge branch!
+
+l!insert(4)
+
+|1,2,3,4: {l}
+
+merge branch!
+
+l!insert(5)
+
+|1,2,3,4,5: {l}
+
+error("cancel merge")

test/tests/checkpoint merging variable.ans

@@ -0,0 +1,24 @@
+:l = 1
+
+:@$ post run check
+	|3: {l}
+
+|1: {l}
+
+l = 2
+
+|2: {l}
+
+merge branch!
+
+l = 3
+
+|3: {l}
+
+merge branch!
+
+l = 4
+
+|4: {l}
+
+error("cancel merge")

test/tests/commit.ans

@@ -0,0 +1,21 @@
+:bar = "bar"!script($_)
+	var = 2
+
+	|before: {var}
+
+	run in new branch("parallel!")
+
+	#foo!checkpoint($_)
+		|checkpoint
+
+	|after: {var}
+
+	run in new branch("parallel!")
+bar.:var = 5
+
+:@$ parallel
+	|parallel: {bar.var}
+
+merge branch!
+
+bar!

test/tests/custom event.ans

@@ -0,0 +1,3 @@
+|ah
+wait(5)
+|ho

test/tests/function conflict.ans

@@ -0,0 +1,5 @@
+:$ f(a, b) 0
+
+:$ f(x) 0
+
+:$ f(a, b) 0

test/tests/function cycle.ans

@@ -0,0 +1,18 @@
+:$ f
+	:a = "a"!script($_)
+		| a
+	:b = "b"!script($_)
+		| b
+	:c = "c"!script($_)
+		| c
+	cycle([a,b,c])
+
+f!
+
+f!
+
+f!
+
+f!
+
+f!

test/tests/function next.ans

@@ -0,0 +1,18 @@
+:$ f
+	:a = "a"!script($_)
+		| a
+	:b = "b"!script($_)
+		| b
+	:c = "c"!script($_)
+		| c
+	next([a, b, c])
+
+f!
+
+f!
+
+f!
+
+f!
+
+f!

test/tests/function random.ans

@@ -0,0 +1,18 @@
+:$ f
+	:a = "a"!script($_)
+		| a
+	:b = "b"!script($_)
+		| b
+	:c = "c"!script($_)
+		| c
+	random([a,b,c])
+
+f!
+
+f!
+
+f!
+
+f!
+
+f!

test/tests/interrupt callback nested paragraph.ans

@@ -0,0 +1,20 @@
+:oh = $
+	|no
+
+oh.:bar = "bar"!script($_)
+	:leave = $
+		|in interrupt: {var}
+
+	var = 2
+
+	|before: {var}
+
+	interrupt("leave!")
+
+	#foo!checkpoint($_)
+		|checkpoint
+
+	|after: {var}
+oh.bar.:var = 5
+
+oh.bar!

test/tests/interrupt callback nested.ans

@@ -0,0 +1,20 @@
+:$ leave
+	|in interrupt: {oh.bar.var}
+
+:$ oh
+	|no
+
+oh.:bar = "bar"!script($_)
+	var = 2
+
+	|before: {var}
+
+	interrupt("leave!")
+
+	#foo!checkpoint($_)
+		|checkpoint
+
+	|after: {var}
+oh.bar.:var = 5
+
+oh.bar!

test/tests/interrupt callback.ans

@@ -0,0 +1,18 @@
+:bar = "bar"!script($_)
+	:var = 5
+
+	var = 2
+
+	:$ leave
+		|in interrupt: {var}
+
+	|before: {var}
+
+	interrupt("leave!")
+
+	#foo!checkpoint($_)
+		|checkpoint
+
+	|after: {var}
+
+bar!

test/tests/interrupt no callback.ans

@@ -0,0 +1,18 @@
+:bar = "bar"!script($_)
+	:var = 5
+
+	var = 2
+
+	:$ leave
+		|in interrupt: {var}
+
+	|before: {var}
+
+	interrupt()
+
+	#foo!checkpoint($_)
+		|checkpoint
+
+	|after: {var}
+
+bar!

test/tests/map index accross checkpoints.ans

@@ -0,0 +1,32 @@
+:f = "f"!script($_)
+	:x = *{4}
+
+	|x={x}
+
+	:a = {1,2,3,(x):4}
+
+	:c = a
+
+	|1={a==c}
+
+	|a(x)={a(x)}
+
+	#ch a!checkpoint
+
+	|a(x)={a(x)}
+
+	#ch b!checkpoint
+
+	x(1) = 3
+
+	|a(x)={a(x)}
+
+	#ch c!checkpoint
+
+	|a(x)={a(x)}
+
+	x={4}
+
+	|no={a(x)}
+
+f!

test/tests/merge nested mutable bis.ans

@@ -0,0 +1,17 @@
+:a = *[1]
+:b = *[2]
+:f = "f"!script($_)
+	a!insert(b)
+
+	#c!checkpoint
+
+	b!insert(3)
+
+	#d!checkpoint
+
+	b!insert(4)
+
+:@$ post run check
+	|[1,[2,3,4]]: {a}
+
+f!

test/tests/merge nested mutable error bis.ans

@@ -0,0 +1,19 @@
+:a = *[1]
+:b = *[2]
+:f = "f"!script($_)
+	a!insert(b)
+
+	#c!checkpoint
+
+	b!insert(3)
+
+	#d!checkpoint
+
+	b!insert(4)
+
+	error("abort")
+
+:@$ post run check
+	|[1,[2,3]]: {a}
+
+f!

test/tests/merge nested mutable error.ans

@@ -0,0 +1,19 @@
+:a = *[1]
+:b = *[2]
+:f = "f"!script($_)
+	a!insert(b)
+
+	#c!checkpoint
+
+	b!insert(3)
+
+	#d!checkpoint
+
+	a!insert(4)
+
+	error("abort")
+
+:@$ post run check
+	|[1,[2,3]]: {a}
+
+f!

test/tests/merge nested mutable.ans

@@ -0,0 +1,17 @@
+:a = *[1]
+:b = *[2]
+:f = "f"!script($_)
+	a!insert(b)
+
+	#c!checkpoint
+
+	b!insert(3)
+
+	#d!checkpoint
+
+	a!insert(4)
+
+:@$ post run check
+	|[1,[2,3],4]: {a}
+
+f!

test/tests/scope checkpoint mutable bis error.ans

@@ -0,0 +1,47 @@
+:x = *[99]
+
+:l = *[1,x]
+
+:n = 0
+
+:$ f(t)
+	t!insert(len(l)+1)
+
+	|f1: {l} {t}
+
+	|CHECK
+	merge branch!
+
+	n < 1 ~
+		|REC
+
+		n += 1
+		f(t)
+
+		|END REC
+
+	|f2: {l}
+
+	|CHECK 2
+	merge branch!
+
+	t!insert(len(t)+1)
+
+	t(2)!insert(len(l)+1)
+
+	error("t")
+
+	|f3: {l} {t}
+
+:@$ post run check
+	|AFTER ERROR
+
+	|l: {l}
+
+f(l)
+
+|FINAL
+
+|l: {l}
+
+|x: {x}

test/tests/scope checkpoint mutable bis.ans

@@ -0,0 +1,40 @@
+:x = *[99]
+
+:l = *[1,x]
+
+:n = 0
+
+:$ f(t)
+	t!insert(len(l)+1)
+
+	|f1: {l} {t}
+
+	|CHECK
+	merge branch!
+
+	n < 1 ~
+		|REC
+
+		n += 1
+		f(t)
+
+		|END REC
+
+	|f2: {l}
+
+	|CHECK 2
+	merge branch!
+
+	t!insert(len(t)+1)
+
+	t(2)!insert(len(l)+1)
+
+	|f3: {l} {t}
+
+f(l)
+
+|FINAL
+
+|l: {l}
+
+|x: {x}

test/tests/scope checkpoint mutable error.ans

@@ -0,0 +1,36 @@
+:l = *[1]
+
+:n = 0
+
+:$ f(t)
+	t!insert(len(l)+1)
+
+	|f1: {l} {t}
+
+	|CHECK
+	merge branch!
+
+	n < 1 ~
+		|REC
+
+		n += 1
+		f(t)
+
+		|END REC
+
+	t!insert(len(t)+1)
+
+	error("t")
+
+	|f2: {l}
+
+:@$ post run check
+	|AFTER ERROR
+
+	|l: {l}
+
+f(l)
+
+|FINAL
+
+|l: {l}

test/tests/scope checkpoint mutable ter error.ans

@@ -0,0 +1,49 @@
+:x = *[99]
+
+:l = *[1,x]
+
+:n = 0
+
+:$ f(t)
+	t!insert(len(l)+1)
+
+	|f1: {l} {t}
+
+	|CHECK
+	merge branch!
+
+	n < 1 ~
+		|REC
+
+		n += 1
+		f(t)
+
+		|END REC
+
+	x!insert(12)
+
+	|f2: {l}
+
+	|CHECK 2
+	merge branch!
+
+	t!insert(len(t)+1)
+
+	t(2)!insert(len(l)+1)
+
+	error("t")
+
+	|f3: {l} {t}
+
+:@$ post run check
+	|AFTER ERROR
+
+	|l: {l}
+
+f(l)
+
+|FINAL
+
+|l: {l}
+
+|x: {x}

test/tests/scope checkpoint mutable ter.ans

@@ -0,0 +1,42 @@
+:x = *[99]
+
+:l = *[1,x]
+
+:n = 0
+
+:$ f(t)
+	t!insert(len(l)+1)
+
+	|f1: {l} {t}
+
+	|CHECK
+	merge branch!
+
+	n < 1 ~
+		|REC
+
+		n += 1
+		f(t)
+
+		|END REC
+
+	x!insert(12)
+
+	|f2: {l}
+
+	|CHECK 2
+	merge branch!
+
+	t!insert(len(t)+1)
+
+	t(2)!insert(len(l)+1)
+
+	|f3: {l} {t}
+
+f(l)
+
+|FINAL
+
+|l: {l}
+
+|x: {x}

test/tests/scope checkpoint mutable.ans

@@ -0,0 +1,29 @@
+:l = *[1]
+
+:n = 0
+
+:$ f(t)
+	t!insert(len(l)+1)
+
+	|f1: {l} {t}
+
+	|CHECK
+	merge branch!
+
+	n < 1 ~
+		|REC
+
+		n += 1
+		f(t)
+
+		|END REC
+
+	t!insert(len(t)+1)
+
+	|f2: {l}
+
+f(l)
+
+|FINAL
+
+|l: {l}

test/tests/seen checkpoint resume.ans

@@ -0,0 +1,12 @@
+: fn = "fn"!script($_)
+	|{run}
+
+	#a!checkpoint
+
+	|a: {run}
+
+fn!from(#a)
+
+fn!from(#a)
+
+fn!from(#a)

test/tests/unseen line.ans

@@ -0,0 +1,7 @@
+: x = "x"!script($_)
+	|a
+	run == 0 ~ |seen only once
+	|b
+
+x!
+x!