Added the bones of EVAL; tried to make cons-cell Seqable - failed

README.md

@@ -2,31 +2,33 @@
 
 LISP 1.5 is to all Lisp dialects as Beowulf is to Emglish literature.
 
+## What this is
+
+A work-in-progress towards an implementation of Lisp 1.5 in Clojure.
+
+## BUT WHY?!!?!
+
+Because.
+
+Because Lisp is the only computer language worth learning, and if a thing is worth learning, it's worth learning properly; which means going back to the beginning and trying to understand that.
+
+Because there is, so far as I know, no working implementation of Lisp 1.5 for modern machines.
+
+Because I'm barking mad, and this is therapy.
+
 ## Installation
 
 Download from http://example.com/FIXME.
 
 ## Usage
 
-FIXME: explanation
+`java -jar beowulf-0.1.0-standalone.jar`
 
-    $ java -jar beowulf-0.1.0-standalone.jar [args]
+## Learning Lisp 1.5
 
-## Options
-
-FIXME: listing of options this app accepts.
-
-## Examples
-
-...
-
-### Bugs
-
-...
-
-### Any Other Sections
-### That You Think
-### Might be Useful
+The `Lisp 1.5 Programmer's Manual` is still
+[in print, ISBN 13 978-0-262-13011-0](https://mitpress.mit.edu/books/lisp-15-programmers-manual); but it's also
+[available online](http://www.softwarepreservation.org/projects/LISP/book/LISP%201.5%20Programmers%20Manual.pdf).
 
 ## License
 

src/beowulf/cons_cell.clj

@@ -3,7 +3,24 @@
 
 (def NIL (symbol "NIL"))
 
-(deftype ConsCell [CAR CDR])
+(deftype ConsCell [CAR CDR]
+  clojure.lang.ISeq
+  (cons [this x] (ConsCell. x this))
+  (count [this] (if
+                 (= (.CDR this) NIL)
+                  0
+                  (inc (count (.CDR this)))))
+  (first [this] (.CAR this))
+  (more [this] (if
+                 (= (.CDR this) NIL)
+                 clojure.lang.PersistentList/EMPTY
+                 (.CDR this)))
+  (next [this] (.CDR this))
+  (seq [this] this) ;; doesn't work - `Method beowulf/cons_cell/ConsCell.seq()Lclojure/lang/ISeq; is abstract`
+
+  clojure.lang.IPersistentCollection
+  (empty [this] false)
+  (equiv [this other] false))
 
 (defn make-cons-cell
   [a d]

src/beowulf/eval.clj

@@ -0,0 +1,25 @@
+(ns beowulf.eval
+  (:require [beowulf.cons-cell :refer [make-beowulf-list make-cons-cell NIL]]))
+
+(declare *oblist* primitive-eval)
+
+
+
+(defn primitive-eval
+  [x]
+  (cond
+    (number? x) x
+    (symbol? x) (@*oblist* x)
+    (instance? x beowulf.cons_cell.ConsCell)
+    (apply (primitive-eval (.CAR x)) (map primitive-eval (.CDR x)))
+    :else
+    (throw (Exception. (str "Don't know how to eval `" x "`")))))
+
+
+(def ^:dynamic *oblist*
+  "The base environment."
+  (atom {'NIL NIL
+         'F NIL
+         'T 'T
+         'eval primitive-eval}))
+