All: add keywords.

Also, fix nth and count to match cloure.

4 files changed, 21 insertions, 4 deletions

diff --git a/r/core.r b/r/core.r
index 74c8f6d..dab36e3 100644
--- a/r/core.r
+++ b/r/core.r
@@ -46,6 +46,13 @@ cons <- function(a,b) {
     new.listl(new_lst)
 }
 
+nth <- function(a,b) {
+    if (b < length(a))
+        a[[b+1]]
+    else
+        throw("nth: index out of range")
+}
+
 do_concat <- function(...) {
     new_lst <- list()
     for(l in list(...)) {
@@ -118,9 +125,10 @@ core_ns <- list(
     "nil?"=.nil_q,
     "true?"=.true_q,
     "false?"=.false_q,
-    "symbol?"=.symbol_q,
     "symbol"=new.symbol,
     "symbol?"=.symbol_q,
+    "keyword"=new.keyword,
+    "keyword?"=.keyword_q,
 
     "pr-str"=pr_str,
     "str"=str,
@@ -155,11 +163,11 @@ core_ns <- list(
     "sequential?"=.sequential_q,
     "cons"=cons,
     "concat"=do_concat,
-    "nth"=function(a,b) if (length(a) < b+1) nil else a[[b+1]],
+    "nth"=nth,
     "first"=function(a) if (length(a) < 1) nil else a[[1]], 
     "rest"=function(a) new.listl(slice(a,2)),
     "empty?"=function(a) .sequential_q(a) && length(a) == 0,
-    "count"=function(a) length(a),
+    "count"=function(a) if (.nil_q(a)) 0 else length(a),
     "apply"=do_apply,
     "map"=map,
     "conj"=conj,
diff --git a/r/printer.r b/r/printer.r
index e684b03..71deef7 100644
--- a/r/printer.r
+++ b/r/printer.r
@@ -27,7 +27,9 @@ if(!exists("..types..")) source("types.r")
             paste("{", .pr_list(hlst, pr, " "), "}", sep="", collapse="")
         },
         "character"={
-            if (print_readably) {
+            if (substring(exp,1,1) == "\u029e") {
+                concat(":", substring(exp,2))
+            } else if (print_readably) {
                 paste("\"",
                       gsub("\\n", "\\\\n",
                            gsub("\\\"", "\\\\\"",
diff --git a/r/reader.r b/r/reader.r
index 780dd4d..7f20288 100644
--- a/r/reader.r
+++ b/r/reader.r
@@ -46,6 +46,8 @@ read_atom <- function(rdr) {
         gsub("\\\\n", "\\n",
              gsub("\\\\\"", "\"",
                   substr(token, 2, nchar(token)-1)))
+    } else if (substr(token,1,1) == ":") {
+        new.keyword(substring(token,2))
     } else if (token == "nil") {
         nil
     } else if (token == "true") {
diff --git a/r/types.r b/r/types.r
index 1f749a5..92d1357 100644
--- a/r/types.r
+++ b/r/types.r
@@ -80,7 +80,12 @@ nil <- structure("malnil", class="nil")
 .true_q <- function(obj) "logical" == class(obj) && obj == TRUE
 .false_q <- function(obj) "logical" == class(obj) && obj == FALSE
 new.symbol <- function(name) structure(name, class="Symbol")
+
 .symbol_q <- function(obj) "Symbol" == class(obj)
+new.keyword <- function(name) concat("\u029e", name)
+.keyword_q <- function(obj) {
+    "character" == class(obj) && "\u029e" == substr(obj,1,1)
+}
 
 # Functions