quasiquote and unquote working.

[scheme.forth.jl.git] / scheme.4th

diff --git a/scheme.4th b/scheme.4th
index bacd8e0..69154f2 100644 (file)
--- a/scheme.4th
+++ b/scheme.4th
@@ -1060,6 +1060,71 @@ parse-idx-stack parse-idx-sp !
 : quote-body ( quote-obj -- quote-body-obj )
     cadr ;
 
+: quasiquote? ( obj -- obj bool )
+    quasiquote-symbol tagged-list? ;
+
+: unquote? ( obj -- obj bool )
+    unquote-symbol tagged-list?
+;
+
+: eval-unquote ( env obj -- res )
+    cdr ( env args )
+
+    nil? if
+        recoverable-exception throw" no arguments to unquote."
+    then
+
+    2dup cdr
+    nil? false = if
+        recoverable-exception throw" too many arguments to unquote."
+    then
+
+    2drop car 2swap eval
+;
+
+defer eval-quasiquote-item
+: eval-quasiquote-list ( env obj -- res )
+    nil? if
+        2swap 2drop exit
+    then
+
+    2over 2over ( env obj env obj )
+
+    car eval-quasiquote-item ( env obj caritem )
+
+    -2rot cdr recurse ( caritem cdritems )
+    cons
+;
+
+:noname ( env obj )
+    unquote? if
+        eval-unquote exit
+    then
+
+    pair-type istype? if
+        eval-quasiquote-list exit
+    then
+
+    2swap 2drop
+; is eval-quasiquote-item
+
+: eval-quasiquote ( obj env -- res )
+    2swap cdr ( env args )
+
+    nil? if
+        recoverable-exception throw" no arguments to quasiquote."
+    then
+
+    2dup cdr ( env args args-cdr )
+    nil? false = if
+        recoverable-exception throw" too many arguments to quasiquote."
+    then
+
+    2drop car ( env arg )
+
+    eval-quasiquote-item
+;
+
 : variable? ( obj -- obj bool )
     symbol-type istype? ;
 
@@ -1346,6 +1411,11 @@ hide env
         exit
     then
 
+    quasiquote? if
+        2swap eval-quasiquote
+        exit
+    then
+
     variable? if
         2swap lookup-var
         exit