fix brainfuck for new tree-il, and add tests

* test-suite/Makefile.am:
* test-suite/tests/brainfuck.test: Add a brainfuck test.

* module/system/base/compile.scm: Also export read-and-compile.

* module/language/tree-il/spec.scm (join): Fix the joiner in the
  0-expression case.

* module/language/tree-il/primitives.scm (+): Recognize (+ x -1) as 1-.

* module/language/brainfuck/parse.scm (read-brainfuck): Return EOF if we
  actually received EOF, and there were no expressions read.

* module/language/brainfuck/compile-tree-il.scm (compile-body): Fix the
  compiler for the new format of "lambda" in tree-il.

module/language/tree-il/primitives.scm

@@ -210,11 +210,15 @@
                  (let ((y (const-exp y)))
                    (and (number? y) (exact? y) (= y 1))))
             (1+ x)
-            (if (and (const? x)
-                     (let ((x (const-exp x)))
-                       (and (number? y) (exact? x) (= x 1))))
-                (1+ y)
-                (+ x y)))
+            (if (and (const? y)
+                 (let ((y (const-exp y)))
+                   (and (number? y) (exact? y) (= y -1))))
+                (1- x)
+                (if (and (const? x)
+                         (let ((x (const-exp x)))
+                           (and (number? y) (exact? x) (= x 1))))
+                    (1+ y)
+                    (+ x y))))
   (x y z . rest) (+ x (+ y z . rest)))
   
 (define-primitive-expander *

module/language/tree-il/spec.scm

@@ -20,6 +20,7 @@
 
 (define-module (language tree-il spec)
   #:use-module (system base language)
+  #:use-module (system base pmatch)
   #:use-module (language glil)
   #:use-module (language tree-il)
   #:use-module (language tree-il compile-glil)
@@ -29,7 +30,10 @@
   (apply write (unparse-tree-il exp) port))
 
 (define (join exps env)
-  (make-sequence #f exps))
+  (pmatch exps
+    (() (make-void #f))
+    ((,x) x)
+    (else (make-sequence #f exps))))
 
 (define-language tree-il
   #:title	"Tree Intermediate Language"