[Ongoing] Rewrite frontend to use Flex/Bison

This is a merge of another experiment, so the changes are large:

- separated "modules" directory into frontend/backend
  - adjusted module names and moved files for this to happen
- removed modules lexer & parser
- removed all the unit tests (most were outdated)
- added Bison, flex, and C development tools to manifest.scm
- added lexer.l, a source file used by the flex utility with a functioning lexing implementation
- added parser.y, a source file used by the bison utility with a functioning parser implementation
- added node.c and node.h, which parser.y uses to construct an AST of a C source file (up to binary ops)
- added driver.c, a Guile-C interface that provides a module to scheme programs
- added a Makefile to make all of this
- added stuff to .gitignore

2 files changed, 0 insertions, 49 deletions

diff --git a/src/modules/tacky/driver.scm b/src/modules/tacky/driver.scm
deleted file mode 100644
index 9696306..0000000
--- a/src/modules/tacky/driver.scm
+++ /dev/null
@@ -1,6 +0,0 @@
-(define-module (tacky driver)
-  #:export (ast->tacky))
-
-
-(define (ast->tacky n)
-  (eval n (resolve-module '(tacky traverse))))
diff --git a/src/modules/tacky/traverse.scm b/src/modules/tacky/traverse.scm
deleted file mode 100644
index 2fd4ca7..0000000
--- a/src/modules/tacky/traverse.scm
+++ /dev/null
@@ -1,43 +0,0 @@
-(define-module (tacky traverse)
-  #:use-module (ast ir)
-  #:export (prog
-            func
-            stmt
-            unary
-            const))
-
-
-(define (prog srout)
-  (list 'prog srout))
-
-(define (func name instrs)
-  (list 'srout name instrs))
-
-(define (stmt val)
-  (list 'instrs
-        (cons 'list (append (cdr val)
-                            (list (list 'ret (car val)))))))
-
-(define (expr op val)
-  (make-instruction op (car val) (cdr val)))
-
-(define (const val)
-  (cons (imm val) '()))
-
-(define (make-instruction op src instrs)
-  (let ((dst (make-temporary)))
-    (cons dst
-          (append instrs
-                  (list (op src dst))))))
-
-(define make-temporary
-  (let ((count 100))
-    (lambda ()
-      (set! count (1+ count))
-      (list 'tmp count))))
-
-(define (neg src dst)
-  (list 'neg src dst))
-
-(define (not src dst)
-  (list 'not src dst))