Incremental checkin, currently not working, just saving progress.

8 files changed, 1142 insertions, 0 deletions

diff --git a/nomnom/ast.nom b/nomnom/ast.nom
new file mode 100644
index 0000000..2d5a894
--- /dev/null
+++ b/nomnom/ast.nom
@@ -0,0 +1,88 @@
+use "lib/object.nom"
+
+#%types = [..]
+    "Number", "Var", "Block", "EscapedNomsu", "Text", "List", "Dict", "DictEntry",
+    "IndexChain", "Action", "FileChunks", "Error", "Comment"
+
+object (Syntax Tree):
+    my action [set up]:
+        if (%me.type == "Action"):
+            %stub_bits = []
+            %argnum = 1
+            for %bit in %me:
+                if:
+                    (%bit is text): %stub_bits::add %bit
+                    (%bit.type != "Comment"):
+                        %stub_bits::add "\%argnum"
+                        %argnum += 1
+            %me.stub = (%stub_bits::joined with " ")
+
+    (Syntax Tree).source_code_for_tree = (..)
+        {} with fallback % -> (read file %.source.filename)
+    
+    my action [children]:
+        %children = []
+        for % in %me:
+            if ((% is a "Syntax Tree") and (%.type != "Comment")):
+                %children::add %
+        if ((%me.type == "Action") and %me.target):
+            %children::add %me.target
+        return %children
+
+    my action [as lua] (..)
+        "Syntax_Tree(\(call ({}'s metatable).as_lua with [%me]))"
+
+    my action [as nomsu] (..)
+        "(Syntax Tree \(call ({}'s metatable).as_nomsu with [%me]))"
+
+    my action [as text] (..)
+        "(Syntax Tree \(call ({}'s metatable).__tostring with [%me]))"
+
+    my action [get source code] (..)
+        (Syntax Tree).source_code_for_tree.%me
+
+    my action [map %fn]:
+        %replacement = (call %fn with [%me])
+        if %replacement:
+            if (%replacement is a "Syntax Tree"):
+                %replacement = (%k = %v for %k = %v in %replacement)
+                %replacement.source = %me.source
+                return (Syntax Tree %replacement)
+            return %replacement
+        ..else:
+            %replacement = {}
+            %changes = (no)
+            for %k = %v in %me:
+                %replacement.%k = %v
+                if (%v is a "Syntax Tree"):
+                    %r = (%v::map %fn)
+                    if ((%r == %v) or (%r == (nil))):
+                        do next %k
+                    %changes = (yes)
+                    %replacement.%k = %r
+            unless %changes: return %me
+            return (Syntax Tree %replacement)
+
+    my action [== %other]:
+        unless (..)
+            all of [..]
+                (type of %me) == (type of %other)
+                (%me's metatable) == (%other's metatable)
+                (size of %me) == (size of %other)
+                %me.type == %other.type
+        ..: return (no)
+        
+        for %item in %me at %i:
+            if (%other.%i != %item): return (no)
+        if (%me.type == "Action"):
+            if (%me.target != %other.target): return (no)
+        return (yes)
+    
+    my action [get args]:
+        assume (%me.type == "Action") or barf "Only actions have arguments, not \(%me.type)"
+        %args = []
+        for % in %me:
+            unless ((% is text) or (%.type == "Comment")):
+                %args::add %
+        return %args
+
diff --git a/nomnom/code_obj.nom b/nomnom/code_obj.nom
new file mode 100644
index 0000000..4df312e
--- /dev/null
+++ b/nomnom/code_obj.nom
@@ -0,0 +1,180 @@
+# This file contains objects that are used to track code positions and incrementally
+    build up generated code, while keeping track of where it came from, and managing
+    indentation levels.
+
+use "lib/object.nom"
+
+object (Code):
+    my action [set up]:
+        %old_bits = %me.bits
+        %me.bits = []
+        if (%me.source is text):
+            %me.source = (Source from text %me.source)
+        for % in %old_bits:
+            %me::add %
+
+    my action [as text]:
+        if (%me.__str == (nil)):
+            set {%buff:[], %indent:0}
+            for % in %me.bits:
+                if (% is text):
+                    %spaces = (%::matching "\n([ ]*)[^\n]*$")
+                    if %spaces.1: %indent = (size of %spaces)
+                ..else:
+                    % = "\%"
+                    if (%indent > 0):
+                        % = (%::with "\n" -> "\n\(" "::* %indent)")
+                %buff::add %
+            %me.__str = (%buff::joined)
+        return %me.__str
+
+    my action [as lua] (..)
+        "\(%me.class.name::as lua id)_1_2(\(%me.source::as lua), \(%me.bits::as lua))"
+
+    my action [as nomsu] (..)
+        "(\(%me.class.name) \(%me.source::as nomsu) \(%me.bits::as nomsu))"
+
+    my action [size] (size of "\%me")
+    
+    my action [mark as dirty]:
+        %me.__str = (nil)
+        %me._trailing_line_len = (nil)
+        %me._num_lines = (nil)
+            
+    my action [add %new_bits]:
+        unless (%new_bits is a "List"):
+            %new_bits = [%new_bits]
+        for % in %new_bits:
+            if (% == ""): do next %
+            if ((% isn't text) and (% isn't a (Code))):
+                % = (%::as lua)
+            %me.bits::add %
+        %me::mark as dirty
+    
+    my action [trailing line length]:
+        if (%me._trailing_line_len == (nil)):
+            %me._trailing_line_len = (size of ("\%me"::matching "[^\n]*$"))
+        return %me._trailing_line_len
+    
+    my action [number of lines]:
+        unless %me._num_lines:
+            %num_lines = 1
+            for % in %me:
+                if (% is text):
+                    %num_lines += (size of (%::all matches of "\n"))
+                ..else:
+                    %num_lines += ((%::number of lines) - 1)
+            %me._num_lines = %num_lines
+        return %me._num_lines
+
+    my action [is multiline, is multi-line] ((%me::number of lines) > 1)
+    my action [is one line, is single line] ((%me::number of lines) == 1)
+
+    my action [add %values joined with %joiner]:
+        %me::add %values joined with %joiner or %joiner
+
+    my action [add %values joined with %joiner or %wrapping_joiner]:
+        %line_len = 0
+        %bits = %me.bits
+        for %i = % in %values:
+            if (%i > 1):
+                if (%line_len > 80):
+                    %bits::add %wrapping_joiner
+                    %line_len = 0
+                ..else:
+                    %bits::add %joiner
+            %bits::add %
+            %line = ("\%"::matching "\n([^\n]*)$")
+            if %line:
+                %line_len = (size of %line)
+            ..else:
+                %line_len += (size of %)
+        %me::mark as dirty
+    
+    my action [prepend %]:
+        if ((% isn't text) and (% isn't a %me.__type)):
+            % = (%::as lua)
+        %me.bits::add % at index 1
+        %me::mark as dirty
+
+    my action [parenthesize]:
+        %me.bits::add "(" at index 1
+        %me.bits::add ")"
+        %me::mark as dirty
+
+
+object (Lua Code) extends (Code):
+    my action [add free vars %vars]:
+        if ((size of %vars) == 0): return
+        %seen = (%v = (yes) for %v in %me.free_vars)
+        for %var in %vars:
+            assume (%var is text)
+            unless %seen.%var:
+                %me.free_vars::add %var
+                %seen.%var = (yes)
+        %me::mark as dirty
+    
+    my action [remove free vars %vars]:
+        if ((size of %vars) == 0): return
+        %removals = {}
+        for %var in %vars:
+            assume (%var is text)
+            %removals.%var = (yes)
+        
+        %stack = [%me]
+        while ((size of %stack) > 0):
+            %lua = (%stack::pop)
+            for %i in (size of %lua.free_vars) to 1 by -1:
+                if %removals.(%lua.%free_vars.%i):
+                    %lua.free_vars::remove index %i
+            for % in %lua.bits:
+                if (% is a "Lua Code"):
+                    %stack::add %
+        %me::mark as dirty
+
+    my action [declare locals]:
+        set {%to_declare:[], %seen:{}}
+        for %lua in recursive %me:
+            for %var in %lua.free_vars:
+                unless %seen.%var:
+                    %seen.%var = (yes)
+                    %to_declare::add %var
+            for % in %lua.bits:
+                if (% is a "Lua Code"):
+                    recurse %lua on %
+        return (%me::declare locals %to_declare)
+
+    my action [declare locals %to_declare]:
+        if ((size of %to_declare) > 0):
+            %me::remove free vars %to_declare
+            %me::prepend "local \(%to_declare::joined with ", ");\n"
+        return %to_declare
+
+    my action [as statements] (%me::as statements "" ";")
+    my action [as statements %prefix] (%me::as statements %prefix ";")
+    my action [as statements %prefix %suffix]:
+        unless %me.is_value:
+            return %me
+        %statements = (Lua Code %me.source [])
+        if (%prefix != ""):
+            %statements::add %prefix
+        %statements::add %me
+        if (%suffix != ""):
+            %statements::add %suffix
+        return %statements
+
+    action [Lua Code from %tree] (..)
+        Lua Code {source:%tree.source, bits:[], is_value:(no), free_vars:[]}
+    action [Lua Code from %tree %bits] (..)
+        Lua Code {source:%tree.source, bits:%bits, is_value:(no), free_vars:[]}
+
+    action [Lua Value from %tree] (..)
+        Lua Code {source:%tree.source, bits:[], is_value:(yes), free_vars:[]}
+    action [Lua Value from %tree %bits] (..)
+        Lua Code {source:%tree.source, bits:%bits, is_value:(yes), free_vars:[]}
+
+object (Nomsu Code) extends (Code):
+    action [Nomsu Code from %tree] (..)
+        Nomsu Code {source:%tree.source, bits:[]}
+    action [Nomsu Code from %tree %bits] (..)
+        Nomsu Code {source:%tree.source, bits:%bits}
diff --git a/nomnom/compile.nom b/nomnom/compile.nom
new file mode 100644
index 0000000..ec48f05
--- /dev/null
+++ b/nomnom/compile.nom
@@ -0,0 +1,207 @@
+# This file contains the code to convert syntax trees to Lua code
+
+use "nomnom/code_obj.nom"
+
+action [compile %tree using %compile_actions]:
+    assume (%tree is a "Syntax Tree")
+    if (..)
+        all of [..]
+            %tree.version, action (Nomsu version)
+            %tree.version != (Nomsu version)
+            action (1 upgraded from 2 to 3)
+    ..: %tree = (upgrade %tree from %tree.version to (Nomsu version))
+    if %tree.type is:
+        "Action":
+            %stub = %tree.stub
+            %compile_action = %compile_actions.%stub
+            if %compile_action:
+                %args = [%tree, %compile_actions]
+                for % in (%tree::get args): %args::add %
+                %result = (call %compile_action with %args)
+                if (%result == (nil)):
+                    compile error at %tree.source "\
+                        ..The compile-time action here (\(%tree.stub)) failed to return any value."
+                    ..hint "\
+                        ..Look at the implementation of (\(%tree.stub)) and make sure it's returning something."
+                if (%result is a "Syntax Tree"):
+                    if (%result == %tree):
+                        compile error at %tree.source "\
+                            ..The compile-time action here (\(%tree.stub)) is producing an endless loop."
+                        ..hint "\
+                            ..Look at the implementation of (\(%tree.stub)) and make sure it's not just returning the original tree."
+                    return (compile %result using %compile_actions)
+                return %result
+
+            %lua = (new Lua Value from %tree)
+            if %tree.target: # Method call
+                %target_lua = (compile %tree.target using %compile_actions)
+                if (("\%target_lua"::matches "^%(.*%)$") or ("\%target_lua"::matches "^[_a-zA-Z][_a-zA-Z0-9]*$")):
+                    %lua::add [%target_lua, ":"]
+                ..else:
+                    %lua::add ["(", %target_lua, "):"]
+            %lua:add [%stub as lua id, "("]
+            %args = []
+            for %tok in %tree:
+                if (%tok is text): do next %tok
+                # TODO: maybe translate Lua comments
+                if (%tok.type == "Comment"): do next %tok
+                if (%tok.type == "Block"):
+                    %values = (..)
+                        (compile %line using %compile_actions) for %line in %tok
+                        ..unless (%line.type == "Comment")
+                    if (all of (%.is_value for % in %values)):
+                        if ((size of %values) == 1):
+                            %arg_lua = %values.1
+                        ..else:
+                            %arg_lua = (new Lua Value from %tok ["("])
+                            %arg_lua::add %values joined with " and nil or "
+                            %arg_lua::add ")"
+                    ..else:
+                        %arg_lua = (new Lua Value from %tok ["((function()"])
+                        for %v in %values at %i:
+                            if %v.is_value:
+                                %v = (%v::as statements ("return " if (%i == (size of %values) else "")))
+                            %arg_lua::add ["\n    ", %v]
+                        %arg_lua::add "\nend)())"
+                ..else:
+                    %arg_lua = (compile %tok using %compile_actions)
+                    unless %arg_lua.is_value:
+                        if (%tok.type == "Action"):
+                            compile error at %tok "\
+                                ..Can't use this as an argument to (\%stub), since it's not \
+                                ..an expression, it produces: \%arg_lua"
+                            ..hint "\
+                                ..Check the implementation of (\(%tok.stub)) to see if it \
+                                ..is actually meant to produce an expression."
+                        ..else:
+                            compile error at %tok "\
+                                ..Can't use this as an argument to (\%stub), since it's \
+                                ..not an expression, it produces: \%arg_lua"
+                %args::add %arg_lua
+            %lua::add %args joined with ", "
+            %lua::add ")"
+            return %lua
+
+        "EscapedNomsu":
+            return (new Lua Value from %tree ((%tree.1)::as nomsu))
+        
+        "Block":
+            %lua = (new Lua Code from %tree)
+            %lua::add (..)
+                ((compile %line using %compile_actions)::as statements)
+                ..for %line in %tree
+            ..joined with "\n"
+            return %lua
+
+        "Text":
+            %lua = (new Lua Code from %tree)
+            %lua_bits = []
+            %string_buffer = ""
+            for % in %tree:
+                if (% is text):
+                    %string_buffer = "\%string_buffer\%"
+                    do next %
+                if (%string_buffer != ""):
+                    %lua_bits::add (%string_buffer::as lua)
+                    %string_buffer = ""
+                %bit_lua = (compile %bit using %compile_actions)
+                unless %bit_lua.is_value:
+                    compile error at %bit "\
+                        ..Can't use this as a string interpolation value, since it doesn't have a value."
+                if (%bit.type != "Text"):
+                    %bit_lua = (new Lua Value from %bit ["tostring(",%bit_lua,")"])
+                %lua_bits::add %bit_lua
+
+            if ((%string_buffer != "") or ((size of %lua_bits) == 0)):
+                %lua_bits::add (%string_buffer::as lua)
+
+            %lua::add %lua_bits joined with ("..")
+            if ((size of %lua_bits) > 1):
+                %lua::parenthesize
+            return %lua
+
+        "List":
+            %lua = (new Lua Value from %tree ["_List{"])
+            %lua::add ((compile % using %compile_actions) for % in %tree) joined with ", " or ",\n  "
+            %lua::add "}"
+            return %lua
+
+        "Dict":
+            %lua = (new Lua Value from %tree ["_Dict{"])
+            %lua::add ((compile % using %compile_actions) for % in %tree) joined with ", " or ",\n  "
+            %lua::add "}"
+            return %lua
+
+        "DictEntry":
+            set {%key:%tree.1, %value:%tree.2}
+            %key_lua = (compile %key using %compile_actions)
+            unless %key_lua.is_value:
+                compile error at %tree.1 "\
+                    ..Can't use this as a dict key, since it's not an expression."
+            %value_lua = (..)
+                (compile %value using %compile_actions) if %value
+                ..else (new Lua Value from %key ["true"]))
+            unless %value_lua.is_value:
+                compile error at %tree.2 "\
+                    ..Can't use this as a dict value, since it's not an expression."
+            %key_str = ("\%key_lua"::matching "^[\"']([a-zA-Z_][a-zA-Z0-9_]*)['\"]$")
+            if:
+                %key_str:
+                    return (new Lua Code from %tree [%key_str, "=", %value_lua])
+                ("\%key_lua".1 == "["):
+                    # NOTE: this *must* use a space after the [ to avoid freaking out
+                        Lua's parser if the inner expression is a long string. Lua
+                        parses x[[[y]]] as x("[y]"), not as x["y"]
+                    return (new Lua Code from %tree ["[ ", %key_lua, "]=", %value_lua])
+                else:
+                    return (new Lua Code from %tree ["[", %key_lua, "]=", %value_lua])
+        
+        "IndexChain":
+            %lua = (compile %tree.1 using %compile_actions)
+            unless %lua.is_value:
+                compile error at %tree.1 "\
+                    ..Can't index into this, since it's not an expression."
+            %first_char = "\%lua".1
+            if (any of [%first_char == "{", %first_char == "\"", %first_char == "["]):
+                %lua::parenthesize
+
+            for %i in 2 to (size of %tree):
+                %key = %tree.%i
+                %key_lua = (compile %key using %compile_actions)
+                unless %key_lua.is_value:
+                    compile error at %key "\
+                        ..Can't use this as an index, since it's not an expression."
+                %key_lua_str = "\%key_lua"
+                %lua_id = (%key_lua_str::matching "^['\"]([a-zA-Z_][a-zA-Z0-9_]*)['\"]$")
+                if:
+                    %lua_id:
+                        %lua::add [".", %lua_id]
+                    (%key_lua_str.1 == "["):
+                        # NOTE: this *must* use a space after the [ to avoid freaking out
+                            Lua's parser if the inner expression is a long string. Lua
+                            parses x[[[y]]] as x("[y]"), not as x["y"]
+                        %lua::add ["[ ", %key_lua, " ]"]
+                    else:
+                        %lua::add ["[", %key_lua, "]"]
+            return %lua
+
+        "Number":
+            return (new Lua Value from %tree ["\(%tree.1)"])
+
+        "Var":
+            return (new Lua Value from %tree [%tree.1::as lua id])
+
+        "FileChunks":
+            barf "\
+                ..Can't convert FileChunks to a single block of lua, since each chunk's \
+                ..compilation depends on the earlier chunks"
+        
+        "Comment":
+            # TODO: implement?
+            return (new Lua Code from %tree)
+        
+        "Error":
+            barf "Can't compile errors"
+
+        else:
+            barf "Unknown type: \(%tree.type)"
diff --git a/nomnom/decompile.nom b/nomnom/decompile.nom
new file mode 100644
index 0000000..27ef406
--- /dev/null
+++ b/nomnom/decompile.nom
@@ -0,0 +1,339 @@
+# This file contains the code to convert syntax trees to Nomsu code
+use "nomnom/code_obj.nom"
+use "nomnom/parser.nom"
+
+# TODO: maybe re-implement the fancy coroutine checker that aborts early if nomsu gets too long
+action [decompile %tree inline]:
+    assume (%tree is a "Syntax Tree")
+    if %tree.type is:
+        "Action":
+            %nomsu = (Nomsu Code from %tree)
+            if %tree.target:
+                %target_nomsu = (decompile %tree.target inline)
+                if %tree.target.type is:
+                    ("Action", "Block"):
+                        %target_nomsu::parenthesize
+                %nomsu::add [%target_nomsu, "::"]
+
+            for %bit in %tree at %i:
+                if (%bit is text):
+                    unless (..)
+                        any of [..]
+                            %i == 1,
+                            %tree.(%i - 1) isn't text,
+                            (%bit::is a nomsu operator) == (%tree.(%i - 1)::is a nomsu operator)
+                    ..: %nomsu::add " "
+                    %nomsu::add %bit
+                ..else:
+                    %arg_nomsu = (decompile %bit inline)
+                    unless ((%i == (size of %tree)) and (%bit.type == "Block")):
+                        %nomsu::add " "
+                        if ((%bit.type == "Action") or (%bit.type == "Block")):
+                            %arg_nomsu::parenthesize
+                    %nomsu::add %arg_nomsu
+            return %nomsu
+
+        "EscapedNomsu":
+            %inner_nomsu = (decompile %tree.1 inline)
+            unless (..)
+                any of [..]
+                    %tree.1.type == "List", %tree.1.type == "Dict",
+                    %tree.1.type == "Var"
+            ..: %inner_nomsu::parenthesize
+            %nomsu = (Nomsu Code from %tree ["\\", %inner_nomsu])
+            return %nomsu
+
+        "Block":
+            %nomsu = (Nomsu Code from %tree [":"])
+            for i,line in ipairs tree
+                %nomsu::add(i == 1 and " " or "; ")
+                %nomsu::add recurse(line, nomsu, i == 1 or i < #tree)
+            return %nomsu
+
+        "Text":
+            %nomsu = (Nomsu Code from %tree ["\""])
+            for %text in recursive %tree:
+                for %bit in %text at %i:
+                    if:
+                        (%bit is text):
+                            %nomsu::add %bit
+                        if %bit.type is:
+                            "Text":
+                                recurse %text on %bit
+                            "Var":
+                                %interp_nomsu = (decompile %bit inline)
+                                # Make sure "...\(%x)y..." isn't confused with "...\(%xy)..."
+                                # TODO: make this more robust against "...\%x\("y").."
+                                if (..)
+                                    (%tree.(%i + 1) is text) and (..)
+                                        not (%tree.(%i + 1)::matches "^[ \n\t,.:;#(){}%[%]]")
+                                ..: %interp_nomsu::parenthesize
+                                %nomsu::add ["\\", %interp_nomsu]
+                            ("List", "Dict"):
+                                %nomsu::add ["\\", decompile %bit inline]
+                            else:
+                                %nomsu::add ["\\(", decompile %bit inline, ")"]
+            return (Nomsu Code from %tree ["\"", %nomsu, "\""])
+
+        ("List", "Dict"):
+            %nomsu = (Nomsu Code from %tree ["[" if (%tree.type == "List") else "{"])
+            for %item in %tree at %i:
+                if (%i > 1): %nomsu::add ", "
+                %nomsu::add (decompile %item inline)
+            %nomsu::add ("]" if (%tree.type == "List") else "}")
+            return %nomsu
+        
+        "DictEntry":
+            set {%key:%tree.1, %value:%tree.2}
+            if (all of [%key.type == "Text", (size of %key) == 1, %key.1::is a nomsu identifier]):
+                %nomsu = (Nomsu Code from %key [key.1])
+            ..else:
+                %nomsu = (decompile %key inline)
+
+            if (%key.type == "Action"):
+                %nomsu::parenthesize
+            %nomsu::add ":"
+            if %value:
+                %nomsu::add (decompile %value inline)
+            return %nomsu
+        
+        "IndexChain":
+            %nomsu = (Nomsu Code from %tree)
+            for %bit in %tree at %i:
+                if (%i > 1): nomsu::add "."
+                if (..)
+                    all of [..]
+                        %i > 1, %bit.type == "Text", (size of %bit) == 1, %bit.1 is text,
+                        %bit.1::is a nomsu identifier
+                    %nomsu::add %bit.1
+                ..else:
+                    %bit_nomsu = (decompile %bit inline)
+                    if (..)
+                        any of [..]
+                            %bit.type == "Action"
+                            %bit.type == "Block"
+                            %bit.type == "IndexChain"
+                            (%bit.type == "Number") and (%i < (size of %tree))
+                    ..: %bit_nomsu::parenthesize
+                    %nomsu::add %bit_nomsu
+            return %nomsu
+        
+        "Number":
+            return (Nomsu Code from %tree [(%tree.1 as hex) if %tree.hex else "\(%tree.1)"])
+
+        "Var":
+            return (Nomsu Code from %tree ["%\(%tree.1)"])
+
+        "Comment":
+            return (nil)
+
+        "FileChunks":
+            barf "Can't inline a FileChunks"
+        
+        "Error":
+            barf "Can't compile errors"
+        
+        else:
+            barf "Unknown type: \(%tree.type)"
+
+%MAX_LINE = 90
+action [decompile %tree]:
+    %nomsu = (Nomsu Code from %tree)
+    # For concision:
+    local action [recurse on %t]:
+        %space = (%MAX_LINE - (%nomsu::trailing line length))
+        if (%space <= 0): go to (Indented)
+        for %subtree in recursive %tree:
+            if %subtree.type is:
+                "Block":
+                    if ((size of %subtree) > 1):
+                        go to (Use Indented)
+                    if ((size of "\(decompile %subtree inline)") > 20):
+                        go to (Use Indented)
+            for %k = %v in %subtree:
+                if (%v is a "Syntax Tree"):
+                    recurse %subtree on %v
+
+        %inline_nomsu = (decompile %t inline)
+        if (%inline_nomsu and ((size of "\%inline_nomsu") <= %space)):
+            return %inline_nomsu
+
+        === (Use Indented) ===
+        %indented = (decompile %t)
+        if (%t.type == "Action"):
+            %indented = (Nomsu Code from %t ["(..)\n    ", %indented])
+        return %indented
+
+    if %tree.type is:
+        "FileChunks":
+            local action [%1 and %2 should clump]:
+                if ((%1.type == "Action") and (%2.type == "Action")):
+                    if (%1.stub == "use 1"): return (%2.stub == "use 1")
+                    if (%1.stub == "test 1"): return (yes)
+                    if (%2.stub == "test 1"): return (no)
+                return (not ((recurse on %1)::is multi-line))
+            for %chunk in %tree at %chunk_no:
+                if (%chunk_no > 1):
+                    %nomsu::add "\n\n\("~"::* 80)\n\n"
+                %nomsu::add (pop comments at %chunk.source.start)
+                if (%chunk.type == "Block"):
+                    for %line in %chunk at %line_no:
+                        if (%line_no > 1):
+                            if (%chunk.(%line_no - 1) and %line should clump):
+                                %nomsu::add ["\n", pop comments at %line.source.start "\n"]
+                            ..else:
+                                %nomsu::add ["\n\n", pop comments at %line.source.start]
+                        %nomsu::add (decompile %line %pop_comments)
+                    %nomsu::add (pop comments at %chunk.source.stop "\n")
+                ..else:
+                    %nomsu::add (decompile %chunk %pop_comments)
+            %nomsu::add (pop comments at %tree.source.stop "\n")
+            unless ("\%nomsu"::matches "\n$"):
+                %nomsu::add "\n"
+            return %nomsu
+
+        "Action":
+            %pos = %tree.source.start
+            %next_space = ""
+            if %tree.target:
+                %target_nomsu = (recurse on %tree.target)
+                if ((%tree.target.type == "Action") and (%target_nomsu::is one line)):
+                    %target_nomsu::parenthesize
+                %nomsu::add %target_nomsu
+                %pos = %tree.target.source.stop
+                %next_space = ("\n..::" if (%target_nomsu::is multi-line) else "::")
+
+            for %bit in %tree at %i:
+                if ((%next_space == " ") and ((%nomsu::trailing line length) > %MAX_LINE)):
+                    %next_space = " \\\n"
+
+                %nomsu::add %next_space
+
+                if (%bit is text):
+                    unless (..)
+                        all of [..]
+                            %tree.(%i - 1) is text
+                            (%tree.(%i - 1)::is a nomsu operator) != (%bit::is a nomsu operator)
+                    ..: %nomsu::add %next_space
+                    %nomsu::add %bit
+                    %next_space = " "
+                    do next %bit
+
+                %bit_nomsu = (recurse on %bit)
+                if (%bit.type == "Comment"):
+                    %next_space = "\n"
+                ..else:
+                    %next_space = (" " if (%bit_nomsu::is one line) else "\n..")
+                    if (%bit.type == "Action"):
+                        %bit_nomsu::parenthesize
+
+            return %nomsu
+
+        "EscapedNomsu":
+            %nomsu::add "\\"
+            %val_nomsu = (recurse on %tree.1)
+            if ((%tree.(1).type == "Action") and (%val_nomsu::is one line)):
+                %val_nomsu::parenthesize
+            %nomsu::add %val_nomsu
+            return %nomsu
+
+        "Block":
+            for %line in %tree at %i:
+                if ((%i > 1) and (%line.type == "Comment")):
+                    %nomsu::add "\n"
+                %line_nomsu = (recurse on %line)
+                %nomsu::add
+                if (%i < (size of %tree)):
+                    if ((%line_nomsu::number of lines) > 2):
+                        %nomsu::add "\n\n"
+                    ..else:
+                        %nomsu::add "\n"
+            return (Nomsu Code from %tree [":\n    ", %nomsu])
+
+        "Text":
+            # Multi-line text has more generous wrap margins
+            %max_line = ((1.5 * %MAX_LINE) rounded down)
+            %nomsu = (Nomsu Code from %tree)
+            local action [add text from %tree]:
+                for %bit in %tree at %i:
+                    if (%bit is text):
+                        # TODO: escape properly?
+                        %bit = (escape text %bit)
+                        for %line in (%bit::lines) at %j:
+                            if:
+                                (%j > 1): nomsu::add "\n"
+                                (((size of %line) > 10) and ((%nomsu::trailing line length) > %max_line)):
+                                    %nomsu::add "\\\n.."
+
+                            while ((size of %line) > 0):
+                                %space = (%max_line - (%nomsu::trailing line length))
+                                %split = (%line::position of "[%p%s]" after %space)
+                                if ((not %split) or (%split > %space + 10)):
+                                    %split = (%space + 10)
+                                if ((%line - %split) < 10):
+                                    %split = (size of %line)
+                                set {%bite:%line.[1, %split], %line:%line.[%split + 1, -1]}
+                                %nomsu::add %bite
+                                if ((size of %line) > 0):
+                                    %nomsu::add "\\\n.."
+                    if (%bit.type == "Text"):
+                        add text from %bit
+                    ..else:
+                        %nomsu::add "\\"
+                        %interp_nomsu = (recurse on %bit)
+                        unless (%interp_nomsu::is multi-line):
+                            if %bit.type is:
+                                "Var":
+                                    if ((%tree.(%i+1) is text) and (not (%tree.(%i+1)::matches "^[ \n\t,.:#(){}[%]]"))):
+                                        %interp_nomsu::parenthesize
+                                ("List", "Dict"):
+                                    %interp_nomsu::parenthesize
+                        %nomsu::add %interp_nomsu
+                        if (%interp_nomsu::is multi-line):
+                            %nomsu::add "\n.."
+            add text from %tree
+            return (Nomsu Code from %tree ["\"\\\n    ..", %nomsu, "\""])
+
+        ("List", "Dict"):
+            if ((size of %tree) == 0):
+                %nomsu::add ("[]" if (%tree.type == "List") else "{}")
+                return %nomsu
+            for %item in %tree at %i:
+                %item_nomsu = (decompile %item inline)
+                if ((not %item_nomsu) or ((size of "\%item_nomsu") > %MAX_LINE)):
+                    %item_nomsu = (recurse on %item_nomsu)
+                %nomsu::add %item_nomsu
+                if (%i < (size of %tree)):
+                    if (..)
+                        (%item_nomsu::is multi-line) or (..)
+                            (%nomsu::trailing line length) + (size of "\%item_nomsu")) >= %MAX_LINE
+                    ..: %nomsu::add "\n"
+                    ..else: %nomsu::add ", "
+            return (..)
+                Nomsu Code from %tree [..]
+                    "[..]\n    " if tree.type == "List" else "{..}\n    "
+                    %nomsu
+        
+        "DictEntry":
+            set {%key:%tree.1, %value:%tree.2}
+            if (all of [%key.type == "Text", (size of %key) == 1, %key.1::is a nomsu identifier]):
+                %nomsu::add %key.1
+            ..else:
+                %nomsu::add (decompile %key inline)
+            if ((%key.type == "Action") or (%key.type == "Block")):
+                %nomsu::parenthesize
+            %nomsu::add [": ", recurse on %value]
+            return %nomsu
+        
+        "Comment":
+            %nomsu::add ["#", %tree.1::with "\n" -> "\n    "]
+            return %nomsu
+        
+        ("IndexChain", "Number", "Var"):
+            return (decompile %tree inline)
+        
+        "Error":
+            barf "Cannot decompile an error"
+        
+        else:
+            barf "Unknown type: \(%tree.type)"
diff --git a/nomnom/files.nom b/nomnom/files.nom
new file mode 100644
index 0000000..8fd8f24
--- /dev/null
+++ b/nomnom/files.nom
@@ -0,0 +1,123 @@
+# Some file utilities for searching for files recursively and using package.nomsupath
+use "lib/os.nom"
+
+%_SPOOFED_FILES = {}
+%_FILE_CACHE = ({} with fallback %_SPOOFED_FILES)
+%_BROWSE_CACHE = {}
+
+# Create a fake file and put it in the cache
+action [spoof file %filename %contents]:
+    %_SPOOFED_FILES.%filename = %contents
+    return %contents
+
+# Read a file's contents
+action [read file %filename]:
+    %contents = %_FILE_CACHE.%filename
+    if %contents: return %contents
+    if (%filename == "stdin"):
+        return (spoof file "stdin" (=lua "io.read('*a')"))
+    %file = (=lua "io.open(\%filename)")
+    unless %file: return (nil)
+    %contents = (call %file.read with [%file, "*a"])
+    %file::close
+    %_FILE_CACHE.%filename = %contents
+    return %contents
+
+action [%path sanitized]:
+    %path = (%path::with "\\" -> "\\\\")
+    %path = (%path::with "`" -> "")
+    %path = (%path::with "\"" -> "\\\"")
+    %path = (%path::with "$" -> "")
+    %path = (%path::with "%.%." -> "\\..")
+    return %path
+
+try:
+    %lfs = (=lua "require('lfs')")
+..and if it succeeds:
+    local action [filesystem has %filename]:
+        %mode = (call %lfs.attributes with [%filename, "mode"])
+        if %mode is:
+            ("file", "directory", "link", "char device"):
+                return (yes)
+            else: return (no)
+    
+    action [file %path exists]:
+        if (..)
+            any of [..]
+                %_SPOOFED_FILES.%path
+                %path == "stdin"
+                filesystem has %path
+        ..: return (yes)
+        for %nomsupath in (%package.nomsupath::all matches of "[^;]+"):
+            if (filesystem has "\%nomsupath/\%path"):
+                return (yes)
+        return (no)
+
+    action [files in %path]:
+        unless %_BROWSE_CACHE.%path:
+            if (%_SPOOFED_FILES.%path or (%filename == "stdin")):
+                %_BROWSE_CACHE.%path = [%path]
+            ..else:
+                if (call %lfs.attributes with [%filename, "mode"]) is:
+                    ("file", "char device"):
+                        %_BROWSE_CACHE.%path = [%filename]
+                    ("directory", "link"):
+                        for %nomsupath in (%package.nomsupath::all matches of "[^;]+"):
+                            %files = []
+                            for %member in (call %lfs.dir with ["\%nomsupath/\%filename"]):
+                                if ((%member == ".") or (%member == "..")):
+                                    do next %member
+                                for % in (files in %member): %files::add %
+                            if ((size of %files) > 0):
+                                %_BROWSE_CACHE.%path = %files
+                                go to (Found Files)
+
+                        %_BROWSE_CACHE.%path = []
+                    else:
+                        %_BROWSE_CACHE.%path = []
+
+        === (Found Files) ===
+        return %_BROWSE_CACHE.%filename
+
+..or if it barfs:
+    # LFS not found! Fall back to shell commands, if available.
+    unless (sh> "find . -maxdepth 0"):
+        url = if jit
+            'https://github.com/spacewander/luafilesystem'
+        else 
+        barf "\
+            ..Could not find 'luafilesystem' module and couldn't run system command 'find' \
+            ..(this might happen on Windows). Please install 'luafilesystem' (which can be \
+            ..found at \(..)
+                "https://github.com/spacewander/luafilesystem"
+                ..if %jit else "https://github.com/keplerproject/luafilesystem"
+            .. or obtained through `luarocks install luafilesystem`)"
+
+
+    action [file %path exists]:
+        if (..)
+            any of [..]
+                %_SPOOFED_FILES.%path
+                %path == "stdin"
+                sh> "ls \(%path sanitized)"
+        ..: return (yes)
+        for %nomsupath in (%package.nomsupath::all matches of "[^;]+"):
+            if (sh> "ls \(%nomsupath)/\(%path)"):
+                return (yes)
+        return (no)
+
+    action [files in %path]:
+        unless %_BROWSE_CACHE.%path:
+            if %_SPOOFED_FILES.%path:
+                %_BROWSE_CACHE.%path = [%_SPOOFED_FILES.%path]
+            ..else:
+                for %nomsupath in (%package.nomsupath::all matches of "[^;]+"):
+                    %files = (sh> "find -L '\%path' -not -path '*/\\.*' -type f'")
+                    if %files:
+                        %_BROWSE_CACHE.%path = (%files::lines)
+                        go to (Found Files)
+                %_BROWSE_CACHE.%path = []
+
+        === (Found Files) ===
+        return %_BROWSE_CACHE.%path
+
diff --git a/nomnom/parser.nom b/nomnom/parser.nom
new file mode 100644
index 0000000..60c356f
--- /dev/null
+++ b/nomnom/parser.nom
@@ -0,0 +1,81 @@
+# This file contains the parser, which converts text into abstract syntax trees
+use "nomonom/ast.nom"
+
+%lpeg = (=lua "require('lpeg')")
+%re = (=lua "require('re')")
+call %lpeg.setmaxstack with [20_000]
+set {..}
+    (action (P 1)): %lpeg.P, (action (R 1)): %lpeg.R, (action (Carg 1)): %lpeg.Carg,
+    (action (Cc 1)): %lpeg.Cc, (action (lpeg re pattern 1)): %re.compile,
+    (action (lpeg re pattern 1 using 2)): %re.compile
+
+%source_code_for_tree = {}
+%defs = (..)
+    {..}
+        nl: (P "\r")^(-1) * (P "\n")
+        tab: P "\t"
+        tonumber: %tonumber
+        tochar: %string.char
+        unpack: %unpack
+        nil: Cc (nil)
+        userdata: Carg 1
+        utf8_char: (..)
+            (R "\194\223")*(R "\128\191") +
+            (R "\224\239")*(R "\128\191")*(R "\128\191") +
+            (R "\240\244")*(R "\128\191")*(R "\128\191")*(R "\128\191")
+
+        Tree: [%t, %userdata] ->:
+            %source = (..)
+                Source {filename:%userdata.filename, start:%tree.start, stop:%tree.stop}
+            set {%t.start: nil, %t.stop: nil}
+            %t = (Syntax Tree %t)
+            (Syntax Tree).source_code_for_tree.%t = %userdata.source
+            return %t
+
+    ..with fallback %key ->:
+        if:
+            (%key::matches "^ascii_(%d+)$"):
+                %i = (%key::matching "^ascii_(%d+)$")
+                return (call %string.char with [%i as a number])
+            (%key::matches "^number_(%d+)$"):
+                %i = (%key::matching "^number_(%d+)$")
+                return (Cc (%i as a number))
+
+%id_patt = (((P "") - (R "09")) *  ((%defs.utf8_char + (R "az") + (R "AZ") + (P "_") + (R "09"))^1 * -1))
+%operator_patt = ((S "'`~!@$^&*+=|<>?/-")^1 * -1)
+%text_methods = (""'s metatable).__index
+%text_methods.(action (is a nomsu identifier)) = (..)
+    [%str] -> (call %id_patt.match with [%id_patt, %str])
+%text_methods.(action (is a nomsu id)) = %text_methods.(action (is a nomsu identifier))
+%text_methods.(action (is a nomsu operator)) = (..)
+    [%str] -> (call %operator_patt.match with [%operator_patt, %str])
+
+%peg_tidier = (..)
+    lpeg re pattern "\
+        file <- %nl* {~ (def/comment) (%nl+ (def/comment))* %nl* ~}
+        def <- anon_def / captured_def
+        anon_def <-
+            ({ident} (" "*) ":" {[^%nl]* (%nl+ " "+ [^%nl]*)*}) 
+            -> "%1 <- %2"
+        captured_def <-
+            ({ident} (" "*) "(" {ident} ")" (" "*) ":" {[^%nl]* (%nl+ " "+ [^%nl]*)*})
+            -> "%1 <- ({| {:start:{}:} %3 {:stop:{}:} {:type: (''->'%2') :} |} %%userdata) -> Tree"
+        ident <- [a-zA-Z_][a-zA-Z0-9_]*
+        comment <- "--" [^%nl]*
+        "
+
+action [make parser from %peg] (make parser from %peg using (nil))
+
+action [make parser from %peg using %make_tree]:
+    %peg = (call %peg_tidier.match with [%peg_tidier, %peg])
+    %peg = (lpeg re pattern %peg using %defs)
+    local action [parse %input from %filename]:
+        %input = "\%input"
+        %tree_mt = {__index: {source:%input, filename:%filename}}
+        %userdata = {..}
+            make_tree: %make_tree or ([%]-> (: set %'s metatable to %tree_mt; return %))
+            filename:%filename, source:%input
+        %tree = (call %peg.match with [%peg, %input, (nil), %userdata])
+        assume %tree or barf "File \%filename failed to parse:\n\%input"
+        return %tree
+    return (action (parse 1 from 2))
diff --git a/nomnom/pretty_errors.nom b/nomnom/pretty_errors.nom
new file mode 100644
index 0000000..732f3b9
--- /dev/null
+++ b/nomnom/pretty_errors.nom
@@ -0,0 +1,75 @@
+# This file has code for converting errors to user-friendly format, with colors,
+    line numbers, code excerpts, and so on.
+
+local action [visible size of %text]:
+    return (size of (%text::with "\027%[[0-9;]*m" -> ""))
+
+local action [boxed %text]:
+    %max_line = (..)
+        max of ((visible size of %line) for %line in (%text::lines))
+    %ret = (..)
+        "\n\%text"::with "\n([^\n]*)" as % -> (..)
+            "\n\%\(" "::* (%max_line - (visible size of %))) \027[0m"
+    return %ret.[2,-1]
+
+action [%err as a pretty error]:
+    %context = 2
+    %err_code = (%err::get source code)
+    %err_line = (%err_code::line at %err.source.start)
+    %err_linenum = (%err_code::line number at %err.source.start)
+    %err_linepos = (%err_code::line position at %err.source.start)
+    # TODO: better handle multi-line errors
+    %err_size = (..)
+        min of [..]
+            %err.source.stop - %err.source.start
+            (size of %err_line) - %err_linepos + 1
+    %nl_indicator = (" " if (%err_linepos > (size of %err_line)) else "")
+    %fmt_str = " %\(size of "\(%err_linenum + %context)")d|"
+    local action [num %i] (%fmt_str::formatted with 0)
+    %linenum_size = (size of (num 0))
+
+    %pointer = "\(" "::* (%err_linepos + %linenum_size - 1))"
+    if (%err_size >= 2):
+        %pointer += "\(%pointer)╚\("═"::* (%err_size - 2))╝"
+    ..else:
+        %pointer += "\(%pointer)⬆"
+
+    %err_msg = "\027[33;41;1m\(%err.title or "Error") at \(%err.source.filename or "???"):\(%err_linenum)\027[0m"
+    for %i in (%err_linenum - %context) to (%err_linenum - 1):
+        %line = (%err_code::line %i)
+        if %line:
+            %err_msg += "\n\027[2m\(num %i)\027[0m\(%line)\027[0m"
+    if %err_line:
+        %before = %err_line.[1, %err_linepos - 1]
+        %during = %err_line.[%err_linepos, %err_linepos + %err_size - 1]
+        %after = %err_line.[%err_linepos + %err_size, -1]
+        %err_line = "\027[0m\(%before)\027[41;30m\(%during)\(%nl_indicator)\027[0m\(%after)"
+        %err_msg += "\n\027[2m\(%fmt_str::formated with %err_linenum)\(%err_line)\027[0m"
+    %err_linenum_end = (%err_code::line number at %err.source.stop)
+    %err_linepos_end = (%err_code::line position at %err.source.stop)
+    %err_linenum_end or= %err_linenum
+    if (%err_linenum_end == %err_linenum):
+        %err_msg += "\n\(%pointer)"
+    ..else:
+        for %i in (%err_linenum + 1) to %err_linenum_end:
+            %line = (%err_code::line %i)
+            if %line:
+                if (%i == %err_linenum_end):
+                    %during = %line.[1, %err_linepos_end - 1]
+                    %after = %line.[%err_linepos_end, -1]
+                    %err_msg += "\n\027[2m\(num %i)\027[0;41;30m\(%during)\027[0m\(%after)"
+                ..else:
+                    %err_msg += "\n\027[2m\(num %i)\027[0;41;30m\(%line)\027[0m"
+
+    %box_width = 70
+    %err_text = "\
+        ..\027[47;31;1m\((" \(%err.error)"::wrapped to %box_width)::with "\n" -> "\n\027[47;31;1m ")"
+    if %err.hint:
+        err_text += "\n\027[47;30m\((" Suggestion: \(%err.hint)"::wrapped to %box_width)::with "\n" -> "\n\027[47;30m ")"
+    %err_msg += "\n\027[33;1m \((%err_text boxed) with "\n" -> "\n ")"
+
+    for %i in (%err_linenum_end + 1) to (%err_linenum_end + %context):
+        %line = (%err_code::line %i)
+        if %line:
+            %err_msg += "\n\027[2m\(num %i)\027[0m\(%line)\027[0m"
+    return %err_msg
diff --git a/nomnom/source.nom b/nomnom/source.nom
new file mode 100644
index 0000000..e05b314
--- /dev/null
+++ b/nomnom/source.nom
@@ -0,0 +1,49 @@
+use "lib/object.nom"
+
+object (Source):
+    action [Source from text %text]:
+        %match = (%text::matching groups "^@(.-)%[(%d+):(%d+)%]$")
+        set {%filename:%match.1, %start:%match.2, %stop:%match.3}
+        unless %filename:
+            %match = (%text::matching groups "^@(.-)%[(%d+)%]$")
+            set {%filename:%match.1, %start:%match.2}
+        return (Source {filename:%filename, start:(%start or 1) as number, stop: %stop as number})
+
+    my action [as text] "\
+        ..@\(%me.filename)[\(%me.start)\(":\(%me.stop)" if %me.stop else "")]"
+
+    my action [as lua] "\
+        ..Source{filename=\(%me.filename::as lua), start=\(%me.start)\
+        ..\(", stop=\(%me.stop)" if %stop else "")}"
+
+    my action [as nomsu] "\
+        ..(Source {filename:\(%me.filename::as nomsu), start:\(%me.start)\
+        ..\(", stop:\(%me.stop)" if %stop else "")})"
+    
+    my action [== %other] (..)
+        all of [..]
+            (%me's metatable) == (%other's metatable)
+            %me.filename == %other.filename
+            %me.start == %other.start
+            %me.stop == %other.stop
+
+    my action [< %other]:
+        assume %me.filename == %other.filename
+        if (%start == %other.start):
+            return ((%me.stop or %me.start) < (%other.stop or %other.start))
+        ..else:
+            return (%me.start < %other.start)
+
+    my action [<= %other]:
+        assume %me.filename == %other.filename
+        if (%start == %other.start):
+            return ((%me.stop or %me.start) <= (%other.stop or %other.start))
+        ..else:
+            return (%me.start <= %other.start)
+
+    my action [+ %offset]:
+        if ((type of %me) == "number"):
+            set {%me:%offset, %offset:%me}
+        ..else:
+            assume (type of %offset) == "number"
+        return (Source {filename:%me.filename, start:%me.start + %offset, stop:%me.stop})