Added `tree` back as a parameter to compile actions, which helps with

better error reporting, e.g. for (fail) (no arguments). Overall better
error reporting now. Also added shorthand ("Action" tree with ...) for
(SyntaxTree {.type = "Action", .1 = ...}).

3 files changed, 55 insertions, 23 deletions

diff --git a/lib/core/errors.nom b/lib/core/errors.nom
index 0b67400..8027228 100644
--- a/lib/core/errors.nom
+++ b/lib/core/errors.nom
@@ -8,14 +8,15 @@ use "core/control_flow"
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-(fail $msg) compiles to
-    LuaCode
-        "at_1_fail(\(quote $msg.source), 'Failure: '..\($msg as lua expr))"
-        ..if $msg else "error('Failure', 0)"
+(fail $msg) compiles to ("
+    at_1_fail(\(quote (this tree).source), 'Failure: \(
+        "'..\($msg as lua expr)" if $msg else "A failure was triggered here'"
+    ))
+")
 
 (assume $condition) compiles to ("
     if not \($condition as lua expr) then
-        at_1_fail(\(quote "\($condition.source)"), "Assumption failed: This is not true.")
+        at_1_fail(\(quote "\($condition.source)"), "Assumption failed: This was not true.")
     end
 ")
 
@@ -24,7 +25,7 @@ use "core/control_flow"
         local _a, _b = \($a as lua expr), \($b as lua expr)
         if _a ~= _b then
             at_1_fail(\(quote "\($a.source)"),
-                "Assumption failed: This value is "..tostring(_a)..", but it was supposed to be "..tostring(_b)..".")
+                "Assumption failed: This value was "..tostring(_a).." when it was supposed to be "..tostring(_b)..".")
         end
     end
 ")
@@ -34,7 +35,7 @@ use "core/control_flow"
         local _a, _b = \($a as lua expr), \($b as lua expr)
         if _a == _b then
             at_1_fail(\(quote "\($a.source)"),
-                "Assumption failed: This value is "..tostring(_a)..", but it wasn't supposed to be.")
+                "Assumption failed: This value was "..tostring(_a).." when it wasn't supposed to be.")
         end
     end
 ")
diff --git a/lib/core/metaprogramming.nom b/lib/core/metaprogramming.nom
index 76ccf4a..bfcc0bf 100644
--- a/lib/core/metaprogramming.nom
+++ b/lib/core/metaprogramming.nom
@@ -16,13 +16,16 @@ lua> ("
             end
         end
     end
-    COMPILE_RULES["define mangler"] = function(\(nomsu environment))
+    COMPILE_RULES["define mangler"] = function(\(nomsu environment), _tree)
         return LuaCode("local mangle = mangler()")
     end
+    COMPILE_RULES["this tree"] = function(\(nomsu environment), _tree)
+        return LuaCode("_tree")
+    end
 ")
 
 lua> ("
-    COMPILE_RULES["1 ->"] = function(\(nomsu environment), \$args, \$body)
+    COMPILE_RULES["1 ->"] = function(\(nomsu environment), _tree, \$args, \$body)
         if \$args and not \$body then \$args, \$body = {}, \$args end
         local body_lua = SyntaxTree:is_instance(\$body) and \(nomsu environment):compile(\$body) or \$body
         if SyntaxTree:is_instance(\$body) and \$body.type ~= "Block" then body_lua:prepend("return ") end
@@ -41,7 +44,7 @@ lua> ("
             elseif not arg_lua:is_lua_id() then
                 at_1_fail(SyntaxTree:is_instance(arg) and arg or nil,
                     "Compile error: This does not compile to a Lua identifier, so it "..
-                    "can't be used as a function argument."..
+                    "can't be used as a function argument. "..
                     "Hint: This should probably be a Nomsu variable instead (like $x).")
             end
             lua:add(i > 1 and ", " or "", arg_lua)
@@ -84,13 +87,29 @@ test:
         fail "compile to is leaking variables"
 
 lua> ("
-    COMPILE_RULES["1 compiles to"] = function(\(nomsu environment), \$action, \$body)
-        local \$args = List{"\(nomsu environment)", unpack(\$action:get_args())}
+    COMPILE_RULES["1 compiles to"] = function(\(nomsu environment), \(this tree), \$action, \$body)
+        local \$args = List{"\(nomsu environment)", "\(this tree)"}
         if \$body.type == "Text" then
             \$body = SyntaxTree{source=\$body.source, type="Action", "Lua", \$body}
         end
-        return LuaCode("COMPILE_RULES[", \$action:get_stub():as_lua(),
-            "] = ", \(\($args -> $body) as lua))
+        if not (\$action.type == "Action" or (\$action.type == "EscapedNomsu" and \$action[1]\
+    ...type == "Action")) then
+            at_1_fail(\$action.source, "Compile error: "..
+                "This is neither an action nor an escaped action. "..
+                "Hint: This should probably be an action like:\\n"
+                .."(foo $x) compiles to \\"(\\\\($x as lua) + 1)\\"")
+        end
+        if \$action.type == "EscapedNomsu" then
+            for _,a in ipairs(\$action[1]) do
+                if a.type == "EscapedNomsu" then \$args:add(a[1]) end
+            end
+            return LuaCode("COMPILE_RULES[", \($action as lua), ":get_stub()] = ",
+                \(\($args -> $body) as lua))
+        else
+            for _,a in ipairs(\$action:get_args()) do \$args:add(a) end
+            return LuaCode("COMPILE_RULES[", \$action:get_stub():as_lua(),
+                "] = ", \(\($args -> $body) as lua))
+        end
     end
 ")
 
@@ -102,19 +121,19 @@ lua> ("
             at_1_fail(\$actions, "Compile error: This should be a list of actions.")
         end
         local lua = \(\($actions.1 compiles to $body) as lua)
-        local \$args = List{"\(nomsu environment)", unpack(\$actions[1]:get_args())}
-        local \$compiled_args = List{"\(nomsu environment)"};
-        for i=2,#\$args do \$compiled_args[i] = \(nomsu environment):compile(\$args[i]) end
+        local \$args = List{"\(nomsu environment)", "\(this tree)", unpack(\$actions[1]:get_args())}
+        local \$compiled_args = List{"\(nomsu environment)", "\(this tree)"};
+        for i=3,#\$args do \$compiled_args[i] = \(nomsu environment):compile(\$args[i]) end
         for i=2,#\$actions do
             local alias = \$actions[i]
-            local \$alias_args = List{"\(nomsu environment)", unpack(alias:get_args())}
+            local \$alias_args = List{"\(nomsu environment)", "\(this tree)", unpack(alias:get_args())}
             lua:add("\\nCOMPILE_RULES[", alias:get_stub():as_lua(), "] = ")
             if \$alias_args == \$args then
                 lua:add("COMPILE_RULES[", \$actions[1]:get_stub():as_lua(), "]")
             else
                 lua:add("function(")
-                local \$compiled_alias_args = List{"\(nomsu environment)"};
-                for i=2,#\$alias_args do \$compiled_alias_args[i] = \(nomsu environment):compile(\$alias_args[i]) end
+                local \$compiled_alias_args = List{"\(nomsu environment)", "\(this tree)"};
+                for i=3,#\$alias_args do \$compiled_alias_args[i] = \(nomsu environment):compile(\$alias_args[i]) end
                 lua:concat_add(\$compiled_alias_args, ", ")
                 lua:add(") return COMPILE_RULES[", \$actions[1]:get_stub():as_lua(), "](")
                 lua:concat_add(\$compiled_args, ", ")
@@ -152,7 +171,7 @@ test:
             lua:add(\$action:get_stub():as_lua_id())
             lua:add_free_vars({\$action:get_stub():as_lua_id()})
         else
-            at_1_fail(\$action, "Compile error: Expected an action or method call here")
+            at_1_fail(\$action, "Compile error: This is not an action or method call.")
         end
         lua:add(" = ", \(\($action -> $body) as lua), ";")
         return lua
@@ -415,6 +434,7 @@ external:
         lua> ("
             local lua_type = \(lua type of $)
             if lua_type == 'string' then return 'Text'
+            elseif lua_type == 'nil' then return 'nil'
             elseif lua_type == 'table' or lua_type == 'userdata' then
                 local mt = getmetatable(\$)
                 if mt and mt.__type then return mt.__type end
@@ -428,6 +448,17 @@ external:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 test:
+    assume ("Action" tree with "foo" ("Var" tree with "x")) == \(foo \$x)
+
+external:
+    ($type tree with (*extra arguments*)) means
+        SyntaxTree (=lua "{type=\$type, ...}")
+    ($type tree from $source) means
+        SyntaxTree (=lua "{type=\$type, source=\$source}")
+    ($type tree from $source with (*extra arguments*)) means
+        SyntaxTree (=lua "{type=\$type, source=\$source, ...}")
+
+test:
     (foo) means:
         return 100 200 300
     assume (select 2 (foo)) == 200
diff --git a/lib/core/things.nom b/lib/core/things.nom
index 104c8d0..5f74b1a 100644
--- a/lib/core/things.nom
+++ b/lib/core/things.nom
@@ -101,8 +101,8 @@ external:
                 $class_body with vars {
                     : for $v in $vars:
                         add ($v as lua expr, text) =
-                            SyntaxTree {.type = "IndexChain"} (SyntaxTree {.type = "Var"} "self")
-                                SyntaxTree {.type = "Index"} (SyntaxTree {.type = "Text"} $v.1)
+                            "IndexChain" tree with ("Var" tree with "self")
+                                "Index" tree with ("Text" tree with $v.1)
                 }
         $lua =
             Lua ("