'''Tcl Assembly Language'''. Assembles into stack-based CISC code.

See [MS's bytecode engine ideas] and [The anatomy of a bytecoded command] for more explanations.

As usual, Tcl's [introspection] helps in learning about TAL:
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% tcl::unsupported::assemble help
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bad instruction "help": must be push, add, append, appendArray, appendArrayStk, appendStk, arrayExistsImm, arrayExistsStk, arrayMakeImm, arrayMakeStk, beginCatch, bitand, bitnot, bitor, bitxor, concat, coroName, currentNamespace, dictAppend, dictExists, dictExpand, dictGet, dictIncrImm, dictLappend, dictRecombineStk, dictRecombineImm, dictSet, dictUnset, div, dup, endCatch, eq, eval, evalStk, exist, existArray, existArrayStk, existStk, expon, expr, exprStk, ge, gt, incr, incrArray, incrArrayImm, incrArrayStk, incrArrayStkImm, incrImm, incrStk, incrStkImm, infoLevelArgs, infoLevelNumber, invokeStk, jump, jump4, jumpFalse, jumpFalse4, jumpTable, jumpTrue, jumpTrue4, label, land, lappend, lappendArray, lappendArrayStk, lappendStk, le, lindexMulti, list, listConcat, listIn, listIndex, listIndexImm, listLength, listNotIn, load, loadArray, loadArrayStk, loadStk, lor, lsetFlat, lsetList, lshift, lt, mod, mult, neq, nop, not, nsupvar, over, pop, pushReturnCode, pushReturnOpts, pushResult, regexp, resolveCmd, reverse, rshift, store, storeArray, storeArrayStk, storeStk, strcmp, streq, strfind, strindex, strlen, strmap, strmatch, strneq, strrange, strrfind, sub, tclooClass, tclooIsObject, tclooNamespace, tclooSelf, tryCvtToNumeric, uminus, unset, unsetArray, unsetArrayStk, unsetStk, uplus, upvar, variable, verifyDict, or yield


** Examples **

[Fib in TAL], by [kbk], 2012-08-21

** Discussion **
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[CMcC]: I've put some incomplete work on tcl script generation of bytecodes here: http://wiki.tcl.tk/_repo/bytecode/

It dates from Apr03, and may not even compile - it's certainly incomplete.

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[Zarutian] 28. oktober 2006: hmm... specifying the grammar of TAL shouldn't be hard.

Backus Naur Forms:
  <statement> ::= [<label>] <instruction> "\n"
  <label>   ::= <alpanumeric string> ":"
  <instruction> ::= <mnemonic name> [<parameter>]*

[AMG]: This is not the final BNF of TAL, if the example on the [assemble] page is any indicator.  It seems the grammar is even simpler than you envision, since `label` is itself a mnemonic.  Another difference is the existence of comments, which seem to go from # to end of line, and semicolons as statement separators.  I'm guessing semicolons and newlines are interchangeable, and semicolons are only strictly needed when multiple statements appear on a line or when a comment appears on the same line as a statement.  I'd like to see a formal definition...

[Zarutian] 28. oktober 2006: Type of instructions needed:
   * Arithmetic and logic operations
   * Input/Output
   * Memory fetching and storage
   * Branching

But the question is: what architecture does TAL target? Tcl bytecodes?

[AK] (Jan 10 2007): AFAIK it would target Tcl bytecodes. As for the grammar, I would say it should be a list representation in general, and anything more formatted can be derived from that, i.e., for display, maybe editing, etc.

[DKF] (same day): It should be noted that currently it is obscenely difficult to manage branching properly, especially when they are forward jumps. It should also be noted that there are some instructions that it is probably difficult to issue outside the main BCC anyway, as they use complex blocks of metadata (especially those relating to foreach loops and switch jump-tables).

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