1 files changed, 31 insertions, 0 deletions
diff --git a/liblali.c b/liblali.c
index e2239dd..87be3d6 100644
--- a/liblali.c
+++ b/liblali.c
@@ -953,6 +953,36 @@ DEFINE_PRIMITIVE_RELATIONAL(primitiveLess,         < , true)
 DEFINE_PRIMITIVE_RELATIONAL(primitiveGreater,      > , true)
 /* DEFINE_PRIMITIVE_RELATIONAL(primitiveGreaterEqual, >=, true) */
 
+Object *primitiveJoin(Object **args, GC_PARAM) {
+  if ((*args)->car == nil)
+    exception("cannot join an empty list");
+  else if ((*args)->car->type != TYPE_CONS)
+    exceptionWithObject((*args)->car, "is not a list");
+
+  unsigned long i = 1;
+  Object *tmpCons = (*args)->car;
+  for (; tmpCons->cdr != nil; tmpCons = tmpCons->cdr)
+    i += strlen(tmpCons->car->string);
+
+  char symbolResult[i];
+  tmpCons = (*args)->car;
+  unsigned long wordLength = strlen(tmpCons->car->string);
+
+  // first list element
+  for (int j = 0; j < wordLength; j++)
+      symbolResult[j] = tmpCons->car->string[j];
+
+  // rest of list elements
+  for (i = wordLength; tmpCons->cdr != nil; tmpCons = tmpCons->cdr) {
+    wordLength = strlen(tmpCons->cdr->car->string);
+    for (int j = 0; j < wordLength; j++)
+      symbolResult[i+j] = tmpCons->cdr->car->string[j];
+    i += wordLength;
+  }
+
+  return newSymbol(symbolResult, GC_ROOTS);
+}
+
 typedef struct Primitive {
   char *name;
   int nMinArgs, nMaxArgs;
@@ -995,6 +1025,7 @@ Primitive primitives[] = {
   /* { "<=",      1, -1, primitiveLessEqual    }, */
   { ">",       1, -1, primitiveGreater      },
   /* { ">=",      1, -1, primitiveGreaterEqual } */
+  { "join",    1,  1, primitiveJoin         },
 };
 
 // Special forms handled by evalExpr. Must be in the same order as above.