X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=d3555a4e1bcdbb2e29ff737addd9ea8efba40eeb;hb=d75e232b614baf3d82abf447daacc8fcefefbe85;hp=e69c63d7c902b640e32d826ef24969f68b1e726e;hpb=d40d4d337456d3a096749cc4dcf23f86944f325f;p=scheme.forth.jl.git

diff --git a/scheme.4th b/scheme.4th
index e69c63d..d3555a4 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -13,7 +13,7 @@ include defer-is.4th
 4 constant nil-type
 5 constant pair-type
 6 constant symbol-type
-: istype? ( obj -- obj b )
+: istype? ( obj type -- obj bool )
     over = ;
 
 \ ------ Memory ------
@@ -51,6 +51,7 @@ variable nextfree
 ;
 
 : nil 0 nil-type ;
+: nil? nil-type istype? ;
 
 : objvar create 0 , 0 , ;
 
@@ -343,9 +344,63 @@ parse-idx-stack parse-idx-sp !
     cons
 ;
 
+: charlist-equiv ( charlist charlist -- bool )
+
+    2over 2over
+
+    \ One or both nil
+    nil? -rot 2drop
+    if
+        nil? -rot 2drop
+        if
+            true exit
+        else
+            false exit
+        then
+    else
+        nil? -rot 2drop
+        if
+            false exit
+        then
+    then
+
+    2over 2over
+
+    \ Neither nil
+    car drop -rot car drop = if
+            cdr 2swap cdr recurse
+        else
+            2drop 2drop false
+    then
+;
+
+: charlist>symbol ( charlist -- symbol-obj )
+
+    symbol-table fetchobj
+
+    begin
+        nil? false =
+    while
+        2over 2over
+        car drop pair-type
+        charlist-equiv if
+            2swap 2drop
+            car
+            exit
+        else
+            cdr
+        then
+    repeat
+
+    2drop
+    drop symbol-type 2dup
+    symbol-table fetchobj cons
+    symbol-table setobj
+;
+
 defer read
 
-: readpair ( -- obj )
+: readpair ( -- pairobj )
     eatspaces
 
     \ Empty lists
@@ -422,12 +477,7 @@ defer read
     then
 
     symbol? if
-        readsymbol
-        drop symbol-type
-        2dup
-        symbol-table fetch
-        cons
-        symbol-table set
+        readsymbol charlist>symbol
         exit
     then