diff --git a/contrib/05.r7rs/CMakeLists.txt b/contrib/05.r7rs/CMakeLists.txt
new file mode 100644
index 00000000..814d80c2
--- /dev/null
+++ b/contrib/05.r7rs/CMakeLists.txt
@@ -0,0 +1,15 @@
+list(APPEND PICLIB_SCHEME_LIBS
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/base.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/cxr.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/read.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/write.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/file.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/case-lambda.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/lazy.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/eval.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/inexact.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/load.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/process-context.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/time.scm
+  ${PROJECT_SOURCE_DIR}/contrib/05.r7rs/scheme/r5rs.scm
+  )
diff --git a/piclib/scheme/base.scm b/contrib/05.r7rs/scheme/base.scm
similarity index 100%
rename from piclib/scheme/base.scm
rename to contrib/05.r7rs/scheme/base.scm
diff --git a/piclib/scheme/case-lambda.scm b/contrib/05.r7rs/scheme/case-lambda.scm
similarity index 100%
rename from piclib/scheme/case-lambda.scm
rename to contrib/05.r7rs/scheme/case-lambda.scm
diff --git a/piclib/scheme/cxr.scm b/contrib/05.r7rs/scheme/cxr.scm
similarity index 100%
rename from piclib/scheme/cxr.scm
rename to contrib/05.r7rs/scheme/cxr.scm
diff --git a/piclib/scheme/eval.scm b/contrib/05.r7rs/scheme/eval.scm
similarity index 100%
rename from piclib/scheme/eval.scm
rename to contrib/05.r7rs/scheme/eval.scm
diff --git a/piclib/scheme/file.scm b/contrib/05.r7rs/scheme/file.scm
similarity index 100%
rename from piclib/scheme/file.scm
rename to contrib/05.r7rs/scheme/file.scm
diff --git a/piclib/scheme/inexact.scm b/contrib/05.r7rs/scheme/inexact.scm
similarity index 100%
rename from piclib/scheme/inexact.scm
rename to contrib/05.r7rs/scheme/inexact.scm
diff --git a/piclib/scheme/lazy.scm b/contrib/05.r7rs/scheme/lazy.scm
similarity index 100%
rename from piclib/scheme/lazy.scm
rename to contrib/05.r7rs/scheme/lazy.scm
diff --git a/piclib/scheme/load.scm b/contrib/05.r7rs/scheme/load.scm
similarity index 100%
rename from piclib/scheme/load.scm
rename to contrib/05.r7rs/scheme/load.scm
diff --git a/piclib/scheme/process-context.scm b/contrib/05.r7rs/scheme/process-context.scm
similarity index 100%
rename from piclib/scheme/process-context.scm
rename to contrib/05.r7rs/scheme/process-context.scm
diff --git a/piclib/scheme/r5rs.scm b/contrib/05.r7rs/scheme/r5rs.scm
similarity index 100%
rename from piclib/scheme/r5rs.scm
rename to contrib/05.r7rs/scheme/r5rs.scm
diff --git a/piclib/scheme/read.scm b/contrib/05.r7rs/scheme/read.scm
similarity index 100%
rename from piclib/scheme/read.scm
rename to contrib/05.r7rs/scheme/read.scm
diff --git a/piclib/scheme/time.scm b/contrib/05.r7rs/scheme/time.scm
similarity index 100%
rename from piclib/scheme/time.scm
rename to contrib/05.r7rs/scheme/time.scm
diff --git a/piclib/scheme/write.scm b/contrib/05.r7rs/scheme/write.scm
similarity index 100%
rename from piclib/scheme/write.scm
rename to contrib/05.r7rs/scheme/write.scm
diff --git a/contrib/10.srfi/CMakeLists.txt b/contrib/10.srfi/CMakeLists.txt
new file mode 100644
index 00000000..1cabb620
--- /dev/null
+++ b/contrib/10.srfi/CMakeLists.txt
@@ -0,0 +1,10 @@
+list(APPEND PICLIB_CONTRIB_LIBS
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/1.scm
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/8.scm
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/17.scm
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/26.scm
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/43.scm
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/60.scm
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/95.scm
+  ${PROJECT_SOURCE_DIR}/contrib/10.srfi/srfi/111.scm
+  )
diff --git a/piclib/srfi/1.scm b/contrib/10.srfi/srfi/1.scm
similarity index 100%
rename from piclib/srfi/1.scm
rename to contrib/10.srfi/srfi/1.scm
diff --git a/piclib/srfi/111.scm b/contrib/10.srfi/srfi/111.scm
similarity index 100%
rename from piclib/srfi/111.scm
rename to contrib/10.srfi/srfi/111.scm
diff --git a/piclib/srfi/17.scm b/contrib/10.srfi/srfi/17.scm
similarity index 100%
rename from piclib/srfi/17.scm
rename to contrib/10.srfi/srfi/17.scm
diff --git a/piclib/srfi/26.scm b/contrib/10.srfi/srfi/26.scm
similarity index 100%
rename from piclib/srfi/26.scm
rename to contrib/10.srfi/srfi/26.scm
diff --git a/piclib/srfi/43.scm b/contrib/10.srfi/srfi/43.scm
similarity index 100%
rename from piclib/srfi/43.scm
rename to contrib/10.srfi/srfi/43.scm
diff --git a/piclib/srfi/60.scm b/contrib/10.srfi/srfi/60.scm
similarity index 100%
rename from piclib/srfi/60.scm
rename to contrib/10.srfi/srfi/60.scm
diff --git a/piclib/srfi/8.scm b/contrib/10.srfi/srfi/8.scm
similarity index 100%
rename from piclib/srfi/8.scm
rename to contrib/10.srfi/srfi/8.scm
diff --git a/piclib/srfi/95.scm b/contrib/10.srfi/srfi/95.scm
similarity index 100%
rename from piclib/srfi/95.scm
rename to contrib/10.srfi/srfi/95.scm
diff --git a/contrib/20.repl/repl.scm b/contrib/20.repl/repl.scm
index d839a7a7..2b9d4812 100644
--- a/contrib/20.repl/repl.scm
+++ b/contrib/20.repl/repl.scm
@@ -16,6 +16,23 @@
       (define (add-history str)
         #f))))
 
+  (eval
+   '(import (scheme base)
+            (scheme load)
+            (scheme process-context)
+            (scheme read)
+            (scheme write)
+            (scheme file)
+            (scheme inexact)
+            (scheme cxr)
+            (scheme lazy)
+            (scheme time)
+            (picrin macro)
+            (picrin dictionary)
+            (picrin array)
+            (picrin library))
+   '(picrin user))
+
   (define (repl)
     (let loop ((buf ""))
       (let ((line (readline (if (equal? buf "") "> " "* "))))
diff --git a/extlib/benz b/extlib/benz
index 0c67a4b7..1d7669a5 160000
--- a/extlib/benz
+++ b/extlib/benz
@@ -1 +1 @@
-Subproject commit 0c67a4b77fcc317a78af4bd40afca591f25a09cb
+Subproject commit 1d7669a5d4a1ece8d73268166917677e99671136
diff --git a/piclib/CMakeLists.txt b/piclib/CMakeLists.txt
index c31da069..5e734f4a 100644
--- a/piclib/CMakeLists.txt
+++ b/piclib/CMakeLists.txt
@@ -1,35 +1,10 @@
 list(APPEND PICLIB_SCHEME_LIBS
-  ${PROJECT_SOURCE_DIR}/piclib/picrin/macro.scm
   ${PROJECT_SOURCE_DIR}/piclib/picrin/base.scm
+  ${PROJECT_SOURCE_DIR}/piclib/picrin/macro.scm
   ${PROJECT_SOURCE_DIR}/piclib/picrin/record.scm
   ${PROJECT_SOURCE_DIR}/piclib/picrin/array.scm
   ${PROJECT_SOURCE_DIR}/piclib/picrin/dictionary.scm
   ${PROJECT_SOURCE_DIR}/piclib/picrin/experimental/lambda.scm
   ${PROJECT_SOURCE_DIR}/piclib/picrin/syntax-rules.scm
   ${PROJECT_SOURCE_DIR}/piclib/picrin/test.scm
-
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/base.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/cxr.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/read.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/write.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/file.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/case-lambda.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/lazy.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/eval.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/inexact.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/load.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/process-context.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/time.scm
-  ${PROJECT_SOURCE_DIR}/piclib/scheme/r5rs.scm
-
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/1.scm
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/8.scm
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/17.scm
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/26.scm
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/43.scm
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/60.scm
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/95.scm
-  ${PROJECT_SOURCE_DIR}/piclib/srfi/111.scm
-
-  ${PROJECT_SOURCE_DIR}/piclib/picrin/user.scm
   )
diff --git a/piclib/picrin/user.scm b/piclib/picrin/user.scm
deleted file mode 100644
index fd1190ff..00000000
--- a/piclib/picrin/user.scm
+++ /dev/null
@@ -1,17 +0,0 @@
-;  the default repl environment
-
-(define-library (picrin user)
-  (import (scheme base)
-          (scheme load)
-          (scheme process-context)
-          (scheme read)
-          (scheme write)
-          (scheme file)
-          (scheme inexact)
-          (scheme cxr)
-          (scheme lazy)
-          (scheme time)
-          (picrin macro)
-          (picrin dictionary)
-          (picrin array)
-          (picrin library)))