PGA - ProGram Algebra

MSP with input/output

MSPio is an extension of MSP with a simple input and output mechanism that abstracts from interacting with the environment, and still is powerful enough.

Additional instructions

read extfocus
Deletes the first character (string of length 1) from the string in focus INPUT and puts it in extfocus.
Returns false on failure.
write "string"
Appends "string" to the string in focus OUTPUT.
write extfocus
Appends the string in extfocus to the string in focus OUTPUT.


The following PGLEc.MSPio program copies INPUT to OUTPUT.
INPUT = "abcde";
+ read x {;
    write x;