A language whose programs are defined entirely by the graph formed by a Git repositories commits. Inspirations: Befunge, Brainfuck, Folders.
(This specification will probably not be stable for a while.)
Two types of data structures are available: A stack, and an endless tape. Both hold signed integers.
Execution starts at the commit pointed to by the master branch. Commit messages can contain a series of single-word instructions, seperated with spaces, which are executed one by one.
After executing a commit with a tag, jump to the branch with the same name (which can be optionally prefixed with "origin/"). Otherwise:
- If a commit has only one parent, execution will continue there after executing all instructions in the current commit.
- If a commit has multiple parents (numbered 1, 2, 3, ...), the top stack element will be popped. If that element is n, to go (n-1)-th parent, or to the last one, if there are less than (n-1) parents.
-
getchar: read char from STDIN and place it on the stack
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putchar: pop top stack element and write it to STDOUT as a char
-
: push ASCII value of that letter on the stack
-
: push the number on the stack
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read: place value of current cell on the stack
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write: pop top stack element and write it to the current cell
-
left: pop top stack value, move left for that many places
-
right: pop top stack value, move right for that many places
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add: pop two topmost stack values, add them, push result on the stack
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sub: pop two topmost stack values, subtract top one from bottom one, push result on the stack
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dup: duplicates topmost stack value
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cmp: pops two top values, pushes 1 if bottommost one is larger, 0 otherwise
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quit: stop the program
You'll need Ruby, and the "rugged" Gem:
gem install rugged
legit comes with some examples, which can unfortunately not be added to this repository, because the programs are Git repositories themselves. To get them, run:
git submodule init
git submodule update
Then, to execute a program, run
ruby interpreter.rb examples/hello/