It looks like you're running into a known limitation of the console. As it says in Section 1.8 - R commands, case sensitivity, etc. of An Introduction to R:
Command lines entered at the console are limited[3] to about 4095 bytes (not characters).
[3] some of the consoles will not allow you to enter more, and amongst those which do some will silently discard the excess and some will use it as the start of the next line.
Either put the command in a file and source it, or break the code into multiple lines by inserting your own newlines at appropriate points (between commas).
The value is hard-coded in src/include/Defn.h : #define CONSOLE_BUFFER_SIZE 4096, so you would need to recompile R to change it.
