missing file

piclib/picrin/macro.scm

@@ -0,0 +1,158 @@
+;;; Hygienic Macros
+
+(define-library (picrin macro)
+  (import (scheme base)
+          (picrin dictionary))
+
+  ;; assumes no derived expressions are provided yet
+
+  (define (memq obj list)
+    (if (null? list)
+        #f
+        (if (eq? obj (car list))
+            list
+            (memq obj (cdr list)))))
+
+  (define (list->vector list)
+    (define vector (make-vector (length list)))
+    (define (go list i)
+      (if (null? list)
+          vector
+          (begin
+            (vector-set! vector i (car list))
+            (go (cdr list) (+ i 1)))))
+    (go list 0))
+
+  (define (vector->list vector)
+    (define (go i)
+      (if (= i (vector-length vector))
+          '()
+          (cons (vector-ref vector i)
+                (go (+ i 1)))))
+    (go 0))
+
+  (define (vector-map proc expr)
+    (list->vector (map proc (vector->list expr))))
+
+  (define (walk proc expr)
+    (if (null? expr)
+        '()
+        (if (pair? expr)
+            (cons (walk proc (car expr))
+                  (walk proc (cdr expr)))
+            (if (vector? expr)
+                (vector-map proc expr)
+                (proc expr)))))
+
+  (define (make-syntactic-closure env free form)
+    (define cache (make-dictionary))
+    (walk
+     (lambda (atom)
+       (if (not (symbol? atom))
+           atom
+           (if (memq atom free)
+               atom
+               (if (dictionary-has? cache atom)
+                   (dictionary-ref cache atom)
+                   (begin
+                     (define id (make-identifier atom env))
+                     (dictionary-set! cache atom id)
+                     id)))))
+     form))
+
+  (define (close-syntax form env)
+    (make-syntactic-closure env '() form))
+
+  (define-syntax capture-syntactic-environment
+    (lambda (form use-env mac-env)
+      (list (cadr form) (list (make-identifier 'quote mac-env) mac-env))))
+
+  (define (sc-macro-transformer f)
+    (lambda (expr use-env mac-env)
+      (make-syntactic-closure mac-env '() (f expr use-env))))
+
+  (define (rsc-macro-transformer f)
+    (lambda (expr use-env mac-env)
+      (make-syntactic-closure use-env '() (f expr mac-env))))
+
+  (define (er-macro-transformer f)
+    (lambda (expr use-env mac-env)
+
+      (define cache (make-dictionary))
+
+      (define (rename sym)
+        (if (dictionary-has? cache sym)
+            (dictionary-ref cache sym)
+            (begin
+              (define id (make-identifier sym mac-env))
+              (dictionary-set! cache sym id)
+              id)))
+
+      (define (compare x y)
+        (if (not (symbol? x))
+            #f
+            (if (not (symbol? y))
+                #f
+                (identifier=? use-env x use-env y))))
+
+      (f expr rename compare)))
+
+  (define (ir-macro-transformer f)
+    (lambda (expr use-env mac-env)
+
+      (define protects (make-dictionary))
+
+      (define (wrap expr)
+        (walk
+         (lambda (atom)
+           (if (not (symbol? atom))
+               atom
+               (begin
+                 (define id (make-identifier atom use-env))
+                 (dictionary-set! protects id atom) ; lookup *atom* from id
+                 id)))
+         expr))
+
+      (define (unwrap expr)
+        (define cache (make-dictionary))
+        (walk
+         (lambda (atom)
+           (if (not (symbol? atom))
+               atom
+               (if (dictionary-has? protects atom)
+                   (dictionary-ref protects atom)
+                   (if (dictionary-has? cache atom)
+                       (dictionary-ref cache atom)
+                       (begin
+                         ;; implicit renaming
+                         (define id (make-identifier atom mac-env))
+                         (dictionary-set! cache atom id)
+                         id)))))
+         expr))
+
+      (define cache (make-dictionary))
+
+      (define (inject sym)
+        (if (dictionary-has? cache sym)
+            (dictionary-ref cache sym)
+            (begin
+              (define id (make-identifier sym use-env))
+              (dictionary-set! cache sym id)
+              id)))
+
+      (define (compare x y)
+        (if (not (symbol? x))
+            #f
+            (if (not (symbol? y))
+                #f
+                (identifier=? mac-env x mac-env y))))
+
+      (unwrap (f (wrap expr) inject compare))))
+
+  (export make-syntactic-closure
+          close-syntax
+          capture-syntactic-environment
+          sc-macro-transformer
+          rsc-macro-transformer
+          er-macro-transformer
+          ir-macro-transformer))