rust: have car and cdr handle 'quote' (hack)

2 files changed, 27 insertions, 10 deletions

diff --git a/minimal.scm b/minimal.scm
index 6e4c3c4..5c953e6 100644
--- a/minimal.scm
+++ b/minimal.scm
@@ -20,7 +20,7 @@
 (define first
   (lambda (p) (car p)))
 
-(define second 
+(define second
   (lambda (p) (car (cdr p))))
 
 (define third
@@ -58,7 +58,7 @@
   (lambda (name table table-f)
     (cond
      ((null? table) (table-f name))
-     (else (lookup-in-entry name 
+     (else (lookup-in-entry name
 			    (car table)
 			    (lambda (n)
 			      (lookup-in-table n (cdr table) table-f)))))))
@@ -105,9 +105,9 @@
 ; need generic true/false booleans, a number type, and a symbol type
 ; also need a mutable "table" collection
 (define *const
-  (lambda (e table) 
-    (cond          
-     ((number? e) e) 
+  (lambda (e table)
+    (cond
+     ((number? e) e)
      ((eq? e #t) #t)
      ((eq? e #f) #f)
      (else (build (quote builtin) e)))))
diff --git a/rust/spectrum.rs b/rust/spectrum.rs
index be41ca8..8325798 100644
--- a/rust/spectrum.rs
+++ b/rust/spectrum.rs
@@ -51,7 +51,7 @@ enum SchemeExpr {
 //////////// Lexing, Parsing, and Printing
 
 fn is_scheme_whitespace(c: char) -> bool{
-    " \r\n".find(c) != None
+    " \t\r\n".find(c) != None
 }
 
 fn is_scheme_sep(c: char) -> bool {
@@ -67,7 +67,7 @@ fn is_valid_identifier(s: &str) -> bool {
         return false;
     }
     for (i, c) in s.chars().enumerate() {
-        if !(c.is_alphabetic() || c == '*' || c == '?' || c == '!' || c == '-' || (c.is_numeric() && i > 0)) {
+        if !( c.is_alphabetic() || "*?!-:".find(c) != None || (c.is_numeric() && i > 0) ) {
             return false;
         }
     }
@@ -535,7 +535,11 @@ fn apply_action(list: &Vec<SchemeExpr>,
                         &SchemeExpr::SchemeList(ref list) => {
                             Ok(list[0].clone())
                         },
-                        _ => Err(format!("car only takes lists"))
+                        &SchemeExpr::SchemeQuote(ref list) => {
+                            Ok(list[0].clone())
+                        },
+                        _ => Err(format!("car only takes lists and quotes (got {})",
+                                         scheme_repr(&args[0]).unwrap()))
                     }
                 },
                 "cdr" => {
@@ -550,7 +554,15 @@ fn apply_action(list: &Vec<SchemeExpr>,
                                 Ok(SchemeExpr::SchemeNull)
                             }
                         },
-                        _ => Err(format!("cdr only takes lists"))
+                        &SchemeExpr::SchemeQuote(ref list) => {
+                            if list.len() > 1 {
+                                Ok(SchemeExpr::SchemeList(list[1..].to_vec()))
+                            } else {
+                                Ok(SchemeExpr::SchemeNull)
+                            }
+                        },
+                        _ => Err(format!("cdr only takes lists and quotes (got {})",
+                                         scheme_repr(&args[0]):unwrap()))
                     }
                 },
                 "cons" => {
@@ -566,7 +578,12 @@ fn apply_action(list: &Vec<SchemeExpr>,
                             ret.extend_from_slice(list);
                             Ok(SchemeExpr::SchemeList(ret))
                         },
-                        _ => Err(format!("cons second arg must be list or null"))
+                        &SchemeExpr::SchemeQuote(ref list) => {
+                            let mut ret = vec![args[0].clone()];
+                            ret.extend_from_slice(list);
+                            Ok(SchemeExpr::SchemeList(ret))
+                        },
+                        _ => Err(format!("cons second arg must be list, quote, or null"))
                     }
                 },
                 "begin" => {