Emit the type declaration file

.gitignore

@@ -1,6 +1,7 @@
 *.o
 *.a
 *.so
+*.d.pln
 
 # lua
 vm/src/lua

run-lint

@@ -25,6 +25,9 @@ for file in \
     examples/*/*.lua  \
     examples/*/*.pln
 do
+    case "$file" in
+        *.d.pln) continue ;;
+    esac
     if grep -n "[$space$tab]$" "$file"; then
         # Forbid trailing whitespace because some editors like to automatically delete it.
         # Such whitespace can cause spurious diffs later down the road, when someone is working on

spec/execution_tests.lua

@@ -25,6 +25,7 @@ function execution_tests.run(compile_file, backend, _ENV, only_compile)
     local file_lua    = modname..".lua"
     local file_script = modname.."script.lua"
     local file_output = modname.."output.txt"
+    local file_d_pln    = modname..".d.pln"
 
     local function compile(body)
         local code = util.render([[
@@ -52,6 +53,7 @@ function execution_tests.run(compile_file, backend, _ENV, only_compile)
         os.remove(file_lua)
         os.remove(file_script)
         os.remove(file_output)
+        os.remove(file_d_pln)
     end)
 
     local assert_test_output = function (expected)

spec/pallenec_spec.lua

@@ -5,6 +5,12 @@
 
 local util = require "pallene.util"
 
+local function file_exists(name)
+   local f = io.open(name, "r")
+   return f ~= nil and io.close(f)
+end
+
+
 describe("pallenec", function()
     before_each(function()
         util.set_file_contents("__test__.pln", [[
@@ -29,7 +35,9 @@ describe("pallenec", function()
         os.remove("__test__.c")
         os.remove("__test__.s")
         os.remove("__test__.so")
+        os.remove("__test__.d.pln")
         os.remove("__test__flag__.so")
+        os.remove("__test__flag__.d.pln")
         os.remove("__test__script__.lua")
         os.remove("__test__script__flag__.lua")
     end)
@@ -61,4 +69,11 @@ describe("pallenec", function()
         assert.is_false(ok, err)
         assert(string.find(abort_msg, "Error: option '--emit-lua' can not be used together with option '--emit-c'", nil, true))
     end)
+
+    it("Can extract type declarations", function()
+        assert(util.execute("pallenec __test__.pln"))
+        assert(file_exists("__test__.d.pln"))
+        local types = util.get_file_contents("__test__.d.pln")
+        assert.equals("f: (integer) -> integer\n", types)
+    end)
 end)