export and export* to create alive modules

See #16

8 files changed, 142 insertions, 45 deletions

diff --git a/alv/base/builtin.moon b/alv/base/builtin.moon
index fd36c69..b9e7e55 100644
--- a/alv/base/builtin.moon
+++ b/alv/base/builtin.moon
@@ -88,7 +88,7 @@ class Builtin
 
     builtin\eval scope, cell\tail!
 
-  __tostring: => "<#{@@__name} #{@head}>"
+  __tostring: => "<#{@@__name}[#{@tag}] #{@head}>"
   __inherited: (cls) => cls.__base.__tostring = @__tostring
 
 {
diff --git a/alv/builtin.moon b/alv/builtin.moon
index ab3a9a0..9b88bd4 100644
--- a/alv/builtin.moon
+++ b/alv/builtin.moon
@@ -7,11 +7,14 @@
 -- @module builtin
 import Builtin, Op, FnDef, Input, val, evt from require 'alv.base'
 import ValueStream, LiteralValue from require 'alv.stream.value'
+import Error from require 'alv.error'
 import Result from require 'alv.result'
 import Cell from require 'alv.cell'
 import Scope from require 'alv.scope'
 import Tag from require 'alv.tag'
 import op_invoke from require 'alv.invoke'
+import load from require 'alv.cycle'
+lfs = require 'lfs'
 
 doc = ValueStream.meta
   meta:
@@ -82,6 +85,16 @@ All arguments have to be evaltime constant."
 
       Result!
 
+load_module = (name, tag) ->
+  Error.wrap "loading module '#{name}'", ->
+    ok, lua = pcall require, "alv-lib.#{name}"
+    if ok
+      ValueStream.wrap lua
+    else
+      result,_ = load.loadfile "#{name}.alv"
+      assert result, "empty return value"
+      result.value
+
 require_ = ValueStream.meta
   meta:
     name: 'require'
@@ -95,11 +108,10 @@ require_ = ValueStream.meta
       assert #tail == 1, "'require' takes exactly one parameter"
 
       result = L\push tail[1]\eval, scope
-      name = result\const!
+      name = result\const!\unwrap 'str'
 
       L\trace @, "loading module #{name}"
-      scope = ValueStream.wrap require "alv-lib.#{name\unwrap 'str'}"
-      Result :value
+      Result value: load_module name, @tag
 
 import_ = ValueStream.meta
   meta:
@@ -115,10 +127,9 @@ current scope."
       L\trace "evaling #{@}"
       assert #tail > 0, "'import' requires at least one arguments"
 
-      for child in *tail
-        name = (child\quote scope)\unwrap 'sym'
-        value = ValueStream.wrap require "alv-lib.#{name}"
-        scope\set name, Result :value
+      for i, child in ipairs tail
+        name = child\quote(scope)\unwrap 'sym'
+        scope\set name, Result value: load_module name, @tag\clone Tag i
       Result!
 
 import_star = ValueStream.meta
@@ -134,14 +145,53 @@ Requires modules `sym1`, `sym2`, … and merges them into the current scope."
       L\trace "evaling #{@}"
       assert #tail > 0, "'import' requires at least one arguments"
 
-
-      for child in *tail
-        name = (child\quote scope)\unwrap 'sym'
-        value = ValueStream.wrap require "alv-lib.#{name}"
+      for i, child in ipairs tail
+        value = load_module child\quote(scope)\unwrap('sym'), @tag\clone Tag i
         scope\use value\unwrap 'scope'
 
       Result!
 
+export_ = ValueStream.meta
+  meta:
+    name: 'export'
+    summary: "Evaluate definitions in a new scope and return it."
+    examples: { '(export expr1 [expr2…])' }
+    description: "
+Evaluate `expr1`, `expr2`, … in a new Scope and return scope."
+
+  value: class  extends Builtin
+    eval: (scope, tail) =>
+      scope = Scope scope
+      children = [expr\eval scope for expr in *tail]
+      Result :children, value: ValueStream.wrap scope
+
+export_star = ValueStream.meta
+  meta:
+    name: 'export*'
+    summary: "Export specific symbol definitions as a module/scope."
+    examples: { '(export* sym1 [sym2…])', '(export*)' }
+    description: "
+Creates a scope containing the symbols `sym1`, `sym2`, … and returns it.
+
+Copies the containing scope if no symbols are given."
+
+  value: class extends Builtin
+    eval: (scope, tail) =>
+      L\trace "evaling #{@}"
+      new_scope = Scope!
+
+      children = if #tail == 0
+        for k,result in pairs scope.values
+          new_scope\set k, result
+          result
+      else
+        for child in *tail
+          name = child\quote(scope)\unwrap 'sym'
+          with result = scope\get name
+            new_scope\set name, result
+
+      Result :children, value: ValueStream.wrap new_scope
+
 fn = ValueStream.meta
   meta:
     name: 'fn'
@@ -185,7 +235,7 @@ function is invoked."
       assert #tail == 3, "'defn' takes exactly three arguments"
       { name, params, body } = tail
 
-      name = (name\quote scope)\unwrap 'sym'
+      name = name\quote(scope)\unwrap 'sym'
       assert params.__class == Cell, "'defn's second argument has to be an expression"
       param_symbols = for param in *params.children
         assert param.type == 'sym', "function parameter declaration has to be a symbol"
@@ -204,7 +254,7 @@ function is invoked."
 
 do_expr = ValueStream.meta
   meta:
-    name: 'do_expr'
+    name: 'do'
     summary: "Evaluate multiple expressions in a new scope."
     examples: { '(do expr1 [expr2…])' }
     description: "
@@ -213,7 +263,8 @@ Evaluate `expr1`, `expr2`, … and return the value of the last expression."
   value: class  extends Builtin
     eval: (scope, tail) =>
       scope = Scope scope
-      Result children: [expr\eval scope for expr in *tail]
+      children = [expr\eval scope for expr in *tail]
+      Result :children, value: children[#children].value
 
 if_ = ValueStream.meta
   meta:
@@ -300,7 +351,7 @@ print = ValueStream.meta
       else
         L\print @inputs.value!
 
-{
+Scope.from_table {
   :doc
   :trace, 'trace!': trace_, :print
 
@@ -308,6 +359,8 @@ print = ValueStream.meta
   require: require_
   import: import_
   'import*': import_star
+  export: export_
+  'export*': export_star
 
   true: ValueStream.meta
     meta:
diff --git a/alv/cell.moon b/alv/cell.moon
index f7e9773..d341dde 100644
--- a/alv/cell.moon
+++ b/alv/cell.moon
@@ -173,6 +173,11 @@ class RootCell extends Cell
   head: => ValueStream.sym 'do'
   tail: => @children
 
+  clone: (parent) =>
+    tag = @tag\clone parent
+    children = [child\clone parent for child in *@children]
+    RootCell tag, children, @white
+
   stringify: =>
     buf = ''
     buf ..= @white[0]
diff --git a/alv/copilot.moon b/alv/copilot.moon
index 3d1523e..e5868bb 100644
--- a/alv/copilot.moon
+++ b/alv/copilot.moon
@@ -6,13 +6,7 @@ lfs = require 'lfs'
 import Scope from require 'alv.scope'
 import Registry from require 'alv.registry'
 import Error from require 'alv.error'
-import program from require 'alv.parsing'
-globals = Scope.from_table require 'alv.builtin'
-
-slurp = (file) ->
-  file = io.open file, 'r'
-  with file\read '*all'
-    file\close!
+import loadfile from require 'alv.load'
 
 spit = (file, str) ->
   file = io.open file, 'w'
@@ -59,14 +53,7 @@ class Copilot
 
   eval: =>
     @registry\begin_eval!
-    ok, ast = Error.try "parsing '#{@file}'", program\match, slurp @file
-    if not (ok and ast)
-      L\print ast or Error 'syntax', "failed to parse"
-      @registry\rollback_eval!
-      return
-
-    scope = Scope globals
-    ok, root = Error.try "evaluating '#{@file}'", ast\eval, scope, @registry
+    ok, root, ast = Error.try "running '#{@file}'", loadfile, @file
     if not ok
       L\print root
       @registry\rollback_eval!
diff --git a/alv/cycle.moon b/alv/cycle.moon
index f5b7e15..dba100f 100644
--- a/alv/cycle.moon
+++ b/alv/cycle.moon
@@ -11,16 +11,21 @@
 -- import somewhere from require 'alv.cycle'
 -- somewhere.Something ...
 --
--- Make sure cycle:load() is called before you access or dereference
+-- Make sure cycle:resolve() is called before you access or dereference
 -- `somewhere`.
 
-load = =>
-  for name, module in pairs @
+unresolved = {}
+
+resolve = =>
+  for name, module in pairs unresolved
     for k, v in pairs require "alv.#{name}"
       module[k] = v
 
+  unresolved = {}
+
 setmetatable {}, __index: (key) =>
-  return load if key == 'load'
+  return resolve if key == 'resolve'
 
   with v = {}
+    rawset unresolved, key, v
     rawset @, key, v
diff --git a/alv/init.moon b/alv/init.moon
index 8b7a01b..f2fed2f 100644
--- a/alv/init.moon
+++ b/alv/init.moon
@@ -9,6 +9,8 @@ if _VERSION == 'Lua 5.1'
       error msg
     a, msg, ...
 
+cycle = require 'alv.cycle'
+
 version = require 'alv.version'
 import Logger from require 'alv.logger'
 import ValueStream, EventStream, IOStream from require 'alv.stream'
@@ -21,11 +23,13 @@ import Tag from require 'alv.tag'
 import Cell, RootCell from require 'alv.cell'
 import program from require 'alv.parsing'
 
-with require 'alv.cycle'
-  \load!
+cycle\resolve!
+
+globals = require 'alv.builtin'
+
+cycle\resolve!
 
 import Copilot from require 'alv.copilot'
-globals = Scope.from_table require 'alv.builtin'
 
 --- exports
 -- @table exports
@@ -61,10 +65,10 @@ globals = Scope.from_table require 'alv.builtin'
     assert (program\match str), Error 'syntax', "failed to parse"
 
   eval: (str, inject) ->
-      scope = Scope nil, globals
-      scope\use inject if inject
+    scope = Scope globals
+    scope\use inject if inject
 
-      ast = assert (program\match str), "failed to parse"
-      result = ast\eval scope
-      result\const!
+    ast = assert (program\match str), "failed to parse"
+    result = ast\eval scope
+    result\const!
 }
diff --git a/alv/load.moon b/alv/load.moon
new file mode 100644
index 0000000..f3f7927
--- /dev/null
+++ b/alv/load.moon
@@ -0,0 +1,43 @@
+----
+-- Functions for loading strings and files of alive code.
+--
+-- @module load
+import Result from require 'alv.result'
+import Builtin from require 'alv.base'
+import Scope from require 'alv.scope'
+import Error from require 'alv.error'
+import program from require 'alv.parsing'
+builtin = require 'alv.builtin'
+
+slurp = (file) ->
+  file = io.open file, 'r'
+  with file\read '*all'
+    file\close!
+
+--- Attempt to load alive code from string.
+--
+-- @tparam string code the code to load
+-- @tparam ?string file name of the source file (for error reporting)
+-- @treturn Result
+-- @treturn AST the parsed and updated AST
+loadstring = (code, file='(unnamed)') ->
+  Error.wrap "evaluating '#{file}'", ->
+    ast = program\match code
+    if not ast
+      error Error 'syntax', "failed to parse"
+
+    scope = Scope builtin
+    result = ast\eval scope
+    result, ast
+
+--- Attempt to load alive code from a file.
+--
+-- @tparam string file filepath of the source file
+-- @treturn Result
+-- @treturn AST the parsed and updated AST
+loadfile = (file) -> loadstring (slurp file), file
+
+{
+  :loadstring
+  :loadfile
+}
diff --git a/docs/gen/index b/docs/gen/index
index 5b06b9d..96f85f0 100755
--- a/docs/gen/index
+++ b/docs/gen/index
@@ -42,7 +42,7 @@ spit OUT, layout
       h2 a "builtins", href: '#builtins'
       p "These definitions are automatically loaded into the global Scope of
         every alive session."
-      ul for key, val in opairs require 'alv.builtin'
-        li render key, ValueStream.wrap val
+      ul for key, val in opairs (require 'alv.builtin').values
+        li render key, val.value
     }
   }