X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=19848b60409e957933ac482f72e87dc803f7a6b2;hb=af4ada618d8d096645f783f40508a1bd6ad0d95d;hp=1953cf98cf0ec004d9bbbe7c4a54acc96b93d4f6;hpb=dc6e0cea1e1e982da8029c94d78ee66ab7e8fd82;p=scheme.forth.jl.git

diff --git a/scheme.4th b/scheme.4th
index 1953cf9..19848b6 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -296,6 +296,17 @@ global-env setobj
     then
 ;
 
+: arg-type-error
+            bold fg red ." Incorrect argument type." reset-term cr
+            abort
+;
+
+: ensure-arg-type ( arg type -- arg )
+    istype? false = if
+        arg-type-error
+    then
+;
+
 include scheme-primitives.4th
 
 \ }}}
@@ -382,8 +393,11 @@ parse-idx-stack parse-idx-sp !
 : minus? ( -- bool )
     nextchar [char] - = ;
 
+: plus? ( -- bool )
+    nextchar [char] + = ;
+
 : fixnum? ( -- bool )
-    minus? if
+    minus? plus? or if
         inc-parse-idx
 
         delim? if
@@ -482,8 +496,11 @@ parse-idx-stack parse-idx-sp !
     nextchar [char] " = ;
 
 : readnum ( -- num-atom )
-    minus? dup if
+    plus? minus? or if
+        minus?
         inc-parse-idx
+    else
+        false
     then
 
     0