9 files changed, 92 insertions(+), 11 deletions(-)

M TODO.org
M rascal.asd
M src/docs.lisp
A src/lang-int.lisp
M src/protocol.lisp
A test/lang-int.lisp
M test/parse.lisp
M test/tests.lisp
A test/utils.lisp

@@ 1,2 1,6 @@
 * rascal Tasks
-** TODO - Figure out how to parse code (from files initially)
+** DONE - Figure out how to parse code (from files initially)
+** TODO - Write an interpreter for lang-int
+** TODO - Add a debugging aid for viewing the AST
+** TODO - Wire up the interpreter and debugging aid to the CLI?
+** TODO - Consider supporting a #!lang directive in parser/program metadata.

@@ 23,6 23,7 @@
                 :components
                 ((:file "protocol")
                  (:file "parse")
+                 (:file "lang-int")
                  (:file "debug")
                  (:file "shell")
                  (:file "docs")


@@ 41,7 42,9 @@
   :components ((:module "test"
                 :serial t
                 :components
-                ((:file "parse")
+                ((:file "utils")
+                 (:file "parse")
+                 (:file "lang-int")
                  (:file "tests"))))
   :perform (test-op (o s)
                     (uiop:symbol-call '#:rascal.test '#:test)))

@@ 10,7 10,8 @@
   (@overview section)
   (rascal.shell:@command section)
   (rascal.protocol:@protocol section)
-  (rascal.parse:@parse section))
+  (rascal.parse:@parse section)
+  (rascal.lang-int:@lang-int section))
 
 (defsection @links (:title "Links")
   "[repo]: https://git.sr.ht/~kingcons/rascal

@@ 0,0 1,44 @@
+(mgl-pax:define-package :rascal.lang-int
+  (:use :cl :alexandria :mgl-pax :trivia :rascal.parse)
+  (:import-from :rascal.protocol
+                #:program
+                #:body
+                #:lint
+                #:interpret))
+
+(in-package :rascal.lang-int)
+
+(defsection @lang-int (:title "Lang-Int")
+  "To start with, we will support a very simple language consisting
+of only integers, addition, subtraction, negation, and simplified input."
+  (*read-handler* variable)
+  (stubbed-read function))
+
+(defvar *read-handler* :cl
+  "The handler to use for READ calls. Should be `:cl` to use cl's READ or
+`:stub` to use STUBBED-READ. Primarily used to ease testing the interpreter.")
+
+(let ((value 0))
+  (defun stubbed-read (&optional new-value)
+    "A substitute for READ. Always returns the value it has closed over, which
+defaults to 0, but can be updated via passing the optional NEW-VALUE arg."
+    (if new-value
+        (setf value new-value)
+        value)))
+
+(defmethod interpret ((program program) (language (eql :lang-int)))
+  (labels ((evaluate (expr)
+             (match expr
+               ((num :value-of value)
+                value)
+               ((primitive :operator 'read)
+                (let ((result (if (eql *read-handler* :cl)
+                                  (read)
+                                  (stubbed-read))))
+                  (unless (integerp result)
+                    (error 'invalid-value "Expected an integer: ~A" result))
+                  result))
+               ((primitive :operator op :args arguments)
+                (let ((args (mapcar #'evaluate arguments)))
+                  (apply op args))))))
+    (evaluate (body program))))

@@ 21,7 21,7 @@ and a method INTERPRET to execute the program via a simple interpreter."
   (interpret generic-function))
 
 (defvar *languages*
-  '(:lang-ints)
+  '(:lang-int)
   "A list of symbols naming all language subsets that rascal supports.")
 
 (defclass program ()

@@ 0,0 1,19 @@
+(defpackage :rascal.test.lang-int
+  (:use :cl :try :rascal.test.utils :rascal.lang-int)
+  (:import-from :rascal.protocol #:parse-program)
+  (:import-from :rascal.protocol #:interpret)
+  (:export #:test-lang-int))
+
+(in-package :rascal.test.lang-int)
+
+(deftest test-lang-int ()
+  (test-example-1))
+
+(deftest test-example-1 ()
+  (let ((example-1 (parse-program (example "lang-int1.ras")))
+        (*read-handler* :stub))
+    (stubbed-read 50)
+    (is (= 42 (interpret example-1 :lang-int)))))
+
+#+nil
+(try 'test-lang-int)

@@ 1,14 1,13 @@
 (defpackage :rascal.test.parse
-  (:use :cl :rascal.protocol :rascal.parse :try)
-  (:import-from :serapeum #:concat)
+  (:use :cl :try :rascal.test.utils :rascal.parse)
+  (:import-from :rascal.protocol
+                #:parse-program
+                #:program
+                #:body)
   (:export #:test-parse))
 
 (in-package :rascal.test.parse)
 
-(defun example (name)
-  (let ((relpath (concat "examples/" name)))
-    (asdf:system-relative-pathname :rascal relpath)))
-
 (deftest test-parse ()
   (test-lang-int-examples))
 

@@ 5,7 5,8 @@
 (in-package :rascal.test)
 
 (deftest test-all ()
-  (rascal.test.parse:test-parse))
+  (rascal.test.parse:test-parse)
+  (rascal.test.lang-int:test-lang-int))
 
 (defun test (&key (debug nil) (print 'unexpected) (describe 'unexpected))
   (warn-on-tests-not-run ((find-package :rascal-test))

@@ 0,0 1,10 @@
+(defpackage :rascal.test.utils
+  (:use :cl :try)
+  (:export #:example))
+
+(in-package :rascal.test.utils)
+
+(defun example (name)
+  "Return the pathname for the rascal program in `examples/` matching NAME."
+  (let ((relpath (serapeum:concat "examples/" name)))
+    (asdf:system-relative-pathname :rascal relpath)))