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What is RDROP in Forth?

I'm new to Forth and I'm using SwiftForth. I am looking for a way to read a matrix from file as described here Writing a text file into an array on Forth, but rdrop is not recognised. Is this exclusive to Gforth or is it part of a library? If it's a library, what are the steps needed to use it?

Solution

  • RDROP is a well known but not standardized word.

    This word can be defined in the following way:

    : rdrop ( R: x -- ) postpone r> postpone drop ; immediate

    A conditional definition in a portable library can look like the following:

    [UNDEFINED] RDROP [IF]
: RDROP ( R: x -- ) POSTPONE R> POSTPONE DROP ; IMMEDIATE
[THEN]