Working on quasiquote.

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

diff --git a/scheme.4th b/scheme.4th
index f2d7375..5d3b778 100644 (file)
--- a/scheme.4th
+++ b/scheme.4th
@@ -52,7 +52,7 @@ variable nextexception
 make-exception recoverable-exception
 make-exception unrecoverable-exception
 
-: display-warning ( addr count -- )
+: display-exception-msg ( addr count -- )
     bold fg red
     ." Exception: "
     type
@@ -65,7 +65,7 @@ make-exception unrecoverable-exception
 
     [compile] if
         ['] -rot ,
-        ['] display-warning ,
+        ['] display-exception-msg ,
     [compile] then
 
     ['] throw ,
@@ -1060,6 +1060,70 @@ 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
+;
+
+: (eval-quasiquote) ( env obj -- res )
+    nil? if
+        2swap 2drop exit
+    then
+
+    2over 2over car ( env obj env obj-car )
+
+    unquote? if
+        eval-unquote
+    else
+        2swap 2drop
+    then
+
+    -2rot cdr ( caritem env cdr )
+    recurse ( caritem cdritems )
+    cons
+;
+
+: 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 )
+
+    unquote? if
+        eval-unquote exit
+    then
+
+    pair-type istype? if
+        (eval-quasiquote) exit
+    then
+
+    2swap 2drop ;
+
 : variable? ( obj -- obj bool )
     symbol-type istype? ;
 
@@ -1346,6 +1410,11 @@ hide env
         exit
     then
 
+    quasiquote? if
+        2swap eval-quasiquote
+        exit
+    then
+
     variable? if
         2swap lookup-var
         exit
@@ -1709,11 +1778,7 @@ variable gc-stack-depth
             recoverable-exception of false endof
             unrecoverable-exception of true endof
 
-            \ Rethrow anything else:
-            throw
-
-            \ If we're still here, loop again
-            false
+            throw false
         endcase
     until
 ;