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Updated readme's, add prototype function declaration operation

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Aidan 2020-07-04 20:41:10 -07:00
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stdlib/Readme.md
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@ -27,6 +27,7 @@ The standard library is loaded during the init step of the repl (or interpreter
[Tokens](https://git.callpipe.com/aidan/shs/-/blob/master/ast/token.go) are a rudimentary linked list of parsed [Lexemes](https://en.wikipedia.org/wiki/Lexeme). In the ast package there are definitions for Tokens, as well as code for the combined Lex/Parse loop that creates them. Tokens are built in a way that makes operating over them with either recursive or iterative alrogithms easy. When consuming Tokens, one can expect their type by looking at the Tag field. The data stored in the Inner field will be either a string or a \*Token depending on what Tag is. You can expect a \*Token if the Tag field is ast.LIST, and a string in all other cases. If the Tag field is ast.SYMBOL you can look it up in the VarTable or the FuncTable. The VarTable will return either a \*Token (if the symbol is a Variable) or *nil* if nothing is found. The FuncTable will return either a \*Function (if there is a match) or it will return *nil*.
P.S.: Ideally a token should not be re-used. You may consider them disposable. It is up to you to make sure that any Token you edit/reuse remains consistant with the type declared in its TAG. Make sure to differentiate between NUMBER and STRING with the `ast.StrIsNumber(arg string) bool` function.
## Adding a function
There are two ways to define functions: Either by writing it in shs code (using the 'func' function) or by extending the standard library. The steps below assume you are extending the standard library.
1. *Write your function in the form of an `ast.Operation`.* Any function that has the defined signature can be an Operation.
2. *Create a `Function` to encapsulate your `Operation`.* Make sure to set the `args` and `name` fields. Args will be used to validate function calls and Name will be used in debug/log output.
3. *Add your `Function` to the `FuncTable`.* Make sure your `Operations`s get added to the table generated in `GenFuncTable`.