Allow argument-less calling using ! suffix

interpreter/expression.lua

@@ -1,6 +1,5 @@
 local expression
 local to_lua, from_lua, eval_text, is_of_type, truthy, format, pretty_type, get_variable, tags, eval_text_callback, events, flatten_list
-local copy
 
 local run
 
@@ -445,6 +444,5 @@ expression = require((...):gsub("interpreter%.expression$", "parser.expression")
 flatten_list = require((...):gsub("interpreter%.expression$", "parser.common")).flatten_list
 local common = require((...):gsub("expression$", "common"))
 to_lua, from_lua, eval_text, is_of_type, truthy, format, pretty_type, get_variable, tags, eval_text_callback, events = common.to_lua, common.from_lua, common.eval_text, common.is_of_type, common.truthy, common.format, common.pretty_type, common.get_variable, common.tags, common.eval_text_callback, common.events
-copy = require((...):gsub("interpreter%.expression$", "common")).copy
 
 return eval

parser/expression.lua

@@ -169,6 +169,8 @@ local function expression(s, state, namespace, current_priority, operating_on)
 					if not args then return args, err end
 					if err:match("[^%s]") then return nil, ("unexpected %q at end of argument list"):format(err) end
 				end
+			elseif r:match("^%!") then -- optional, to call with no arg, no explicit call
+				r = r:match("^%!(.*)$")
 			end
 			-- find compatible variant
 			local variant, err = find_function(state, namespace, name, args, explicit_call)
@@ -314,18 +316,27 @@ local function expression(s, state, namespace, current_priority, operating_on)
 			end
 		end
 		-- index / call
-		if s:match("^%b()") then
-			local content, r = s:match("^(%b())(.*)$")
-			content = content:gsub("^%(", ""):gsub("%)$", "")
-			-- get arguments
+		if s:match("^%b()") or s:match("^%!") then
 			local args = operating_on
-			if content:match("[^%s]") then
-				local right, r_paren = expression(content, state, namespace)
-				if not right then return right, r_paren end
-				if r_paren:match("[^%s]") then return nil, ("unexpected %q at end of index/call expression"):format(r_paren) end
-				args = { type = "list", left = args, right = right }
+			local explicit_call, r
+			-- call with args, explicit call
+			if s:match("^%b()") then
+				explicit_call = true
+				local content
+				content, r = s:match("^(%b())(.*)$")
+				content = content:gsub("^%(", ""):gsub("%)$", "")
+				-- get arguments
+				if content:match("[^%s]") then
+					local right, r_paren = expression(content, state, namespace)
+					if not right then return right, r_paren end
+					if r_paren:match("[^%s]") then return nil, ("unexpected %q at end of index/call expression"):format(r_paren) end
+					args = { type = "list", left = args, right = right }
+				end
+			-- call with no arg, no explicit call
+			elseif s:match("^%!") then
+				r = s:match("^%!(.*)$")
 			end
-			local variant, err = find_function(state, namespace, "()", args, true)
+			local variant, err = find_function(state, namespace, "()", args, explicit_call)
 			if not variant then return variant, err end
 			return expression(r, state, namespace, current_priority, variant)
 		end

stdlib/functions.lua

@@ -119,6 +119,9 @@ functions = {
 			return v
 		end
 	},
+	["()(fn::function reference, l...)"] = {
+		-- bypassed, this case is manually handled in the expression interpreter
+	},
 	-- format
 	["{}(v)"] = {
 		mode = "raw",

test/tests/function reference call explicit call.ans

@@ -0,0 +1,12 @@
+$ fn
+	1
+	§ c
+	2
+
+:c = &fn
+
+~ c!
+
+~ c()
+
+~ c!

test/tests/function reference call explicit call.lua

@@ -0,0 +1,40 @@
+local _={}
+_[17]={}
+_[16]={}
+_[15]={}
+_[14]={}
+_[13]={}
+_[12]={text="2",tags=_[17]}
+_[11]={text="2",tags=_[16]}
+_[10]={text="1",tags=_[15]}
+_[9]={text="2",tags=_[14]}
+_[8]={text="1",tags=_[13]}
+_[7]={_[12]}
+_[6]={_[10],_[11]}
+_[5]={_[8],_[9]}
+_[4]={"return"}
+_[3]={"text",_[7]}
+_[2]={"text",_[6]}
+_[1]={"text",_[5]}
+return {_[1],_[2],_[3],_[4]}
+--[[
+{ "text", { {
+      tags = {},
+      text = "1"
+    }, {
+      tags = {},
+      text = "2"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "1"
+    }, {
+      tags = {},
+      text = "2"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "2"
+    } } }
+{ "return" }
+]]--

test/tests/function reference call.lua

@@ -17,24 +17,24 @@ _[41]={}
 _[40]={}
 _[39]={}
 _[38]={}
-_[37]={text="8",tags=_[55]}
-_[36]={text="8: ",tags=_[54]}
-_[35]={text="7",tags=_[53]}
-_[34]={text="7: ",tags=_[52]}
-_[33]={text="13",tags=_[51]}
-_[32]={text="13: ",tags=_[50]}
-_[31]={text="5",tags=_[49]}
-_[30]={text="5: ",tags=_[48]}
-_[29]={text="4",tags=_[47]}
-_[28]={text="4: ",tags=_[46]}
-_[27]={text="4",tags=_[45]}
-_[26]={text="4: ",tags=_[44]}
-_[25]={text="5",tags=_[43]}
-_[24]={text="5: ",tags=_[42]}
-_[23]={text="3",tags=_[41]}
-_[22]={text="3: ",tags=_[40]}
-_[21]={text="3",tags=_[39]}
-_[20]={text="3: ",tags=_[38]}
+_[37]={tags=_[55],text="8"}
+_[36]={tags=_[54],text="8: "}
+_[35]={tags=_[53],text="7"}
+_[34]={tags=_[52],text="7: "}
+_[33]={tags=_[51],text="13"}
+_[32]={tags=_[50],text="13: "}
+_[31]={tags=_[49],text="5"}
+_[30]={tags=_[48],text="5: "}
+_[29]={tags=_[47],text="4"}
+_[28]={tags=_[46],text="4: "}
+_[27]={tags=_[45],text="4"}
+_[26]={tags=_[44],text="4: "}
+_[25]={tags=_[43],text="5"}
+_[24]={tags=_[42],text="5: "}
+_[23]={tags=_[41],text="3"}
+_[22]={tags=_[40],text="3: "}
+_[21]={tags=_[39],text="3"}
+_[20]={tags=_[38],text="3: "}
 _[19]={_[36],_[37]}
 _[18]={_[34],_[35]}
 _[17]={_[32],_[33]}