X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=6d56d6422ad815f4562cc855614888c7e74f7790;hb=df155ab91981bf03189b8e63c342b80640f0fe67;hp=e69c63d7c902b640e32d826ef24969f68b1e726e;hpb=d40d4d337456d3a096749cc4dcf23f86944f325f;p=scheme.forth.jl.git

diff --git a/scheme.4th b/scheme.4th
index e69c63d..6d56d64 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -13,12 +13,12 @@ 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 ------
 
-100 constant N
+1000 constant N
 create car-cells N allot
 create car-type-cells N allot
 create cdr-cells N allot
@@ -50,7 +50,13 @@ variable nextfree
     cdr-type-cells + @
 ;
 
+: caar car car ;
+: cadr cdr car ;
+: cdar car cdr ;
+: cddr cdr cdr ;
+
 : nil 0 nil-type ;
+: nil? nil-type istype? ;
 
 : objvar create 0 , 0 , ;
 
@@ -64,6 +70,42 @@ variable nextfree
 objvar symbol-table
 nil symbol-table setobj
 
+: objeq? ( obj obj -- bool )
+    rot = -rot = and ;
+
+\ ---- Pre-defined symbols ----
+
+: (create-symbol) ( addr n -- symbol-obj )
+    dup 0= if
+        2drop nil
+    else
+        2dup drop @ character-type 2swap
+        swap 1+ swap 1-
+        recurse
+
+        cons
+    then
+;
+
+: create-symbol ( -- )
+    bl word
+    count
+
+    (create-symbol)
+    drop symbol-type
+
+    2dup
+
+    symbol-table fetchobj
+    cons
+    symbol-table setobj
+
+    create swap , ,
+    does> dup @ swap 1+ @
+;
+
+create-symbol quote quote
+
 \ ---- Read ----
 
 variable parse-idx
@@ -233,30 +275,6 @@ parse-idx-stack parse-idx-sp !
 : string? ( -- bool )
     nextchar [char] " = ;
 
-: initial? ( -- bool )
-    nextchar [char] A >= nextchar [char] Z <= and if true exit then
-    nextchar [char] a >= nextchar [char] z <= and if true exit then
-    nextchar [char] * = if true exit then
-    nextchar [char] / = if true exit then
-    nextchar [char] > = if true exit then
-    nextchar [char] < = if true exit then
-    nextchar [char] = = if true exit then
-    nextchar [char] ? = if true exit then
-    nextchar [char] ! = if true exit then
-    false
-;
-
-: symbol? ( -- bool )
-    initial? if true exit then
-    nextchar [char] + =
-    nextchar [char] - = or if
-        inc-parse-idx
-        delim? if dec-parse-idx true exit then
-        dec-parse-idx
-    then
-    false
-;
-
 : readnum ( -- num-atom )
     minus? dup if
         inc-parse-idx
@@ -343,9 +361,63 @@ 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
+            2drop 2drop true exit
+        else
+            2drop 2drop false exit
+        then
+    else
+        nil? -rot 2drop
+        if
+            2drop 2drop 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
@@ -421,16 +493,6 @@ defer read
         exit
     then
 
-    symbol? if
-        readsymbol
-        drop symbol-type
-        2dup
-        symbol-table fetch
-        cons
-        symbol-table set
-        exit
-    then
-
     pair? if
         inc-parse-idx
 
@@ -450,29 +512,57 @@ defer read
         exit
     then
 
+    nextchar [char] ' = if
+        inc-parse-idx
+        quote recurse nil cons cons exit
+    then
+
     eof? if
         bold fg blue ." Moriturus te saluto." reset-term ."  ok" cr
         quit
     then
 
-    bold fg red ." Error parsing string starting at character '"
-    nextchar emit
-    ." '. Aborting." reset-term cr
-    abort
+    \ Anything else is assumed to be a symbol
+    readsymbol charlist>symbol
 
 ; is read
 
 \ ---- Eval ----
 
 : self-evaluating? ( obj -- obj bool )
-    true \ everything self-evaluating for now
+    boolean-type istype? if true exit then
+    number-type istype? if true exit then
+    character-type istype? if true exit then
+    string-type istype? if true exit then
+    nil-type istype? if true exit then
+
+    false
 ;
 
+: tagged-list? ( obj tag-obj -- obj bool )
+    2over 
+    pair-type istype? false = if
+        2drop 2drop false
+    else
+        car objeq?
+    then ;
+
+: quote? ( obj -- obj bool )
+    quote tagged-list?  ;
+
+: quote-body ( quote-obj -- quote-body-obj )
+    cadr ;
+    
 : eval
     self-evaluating? if
         exit
     then
 
+    quote? if
+        quote-body
+        exit
+    then
+
     bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr
     abort
 ;