Add args() builtin for getting argv[]

SPEC.md

@@ -149,6 +149,7 @@ These are the right primitives, but we can build much more sophisticated systems
 
 ### System interfaces
 
+- `args() => list`: argv of the currently running process
 - `in(callback<string> => boolean)`: Read from stdin. The callback function returns a boolean that determines whether to continue reading from input.
 - `out(string)`: Print to stdout.
 - `dir(string, callback<list>)`: List the contents of a directory. The callback gets a list of values of the form `{name: string, len: number, dir: boolean}`. Effectively `stat()` for all files in the directory.

pkg/ink/runtime.go

@@ -49,6 +49,7 @@ func (ctx *Context) LoadEnvironment() {
 	ctx.LoadFunc("load", inkLoad)
 
 	// system interfaces
+	ctx.LoadFunc("args", inkArgs)
 	ctx.LoadFunc("in", inkIn)
 	ctx.LoadFunc("out", inkOut)
 	ctx.LoadFunc("dir", inkDir)
@@ -143,6 +144,14 @@ func inkLoad(ctx *Context, in []Value) (Value, error) {
 	}
 }
 
+func inkArgs(ctx *Context, in []Value) (Value, error) {
+	comp := CompositeValue{}
+	for i, v := range os.Args {
+		comp[nToS(float64(i))] = StringValue(v)
+	}
+	return comp, nil
+}
+
 func inkIn(ctx *Context, in []Value) (Value, error) {
 	if len(in) != 1 {
 		return nil, Err{

samples/test.ink

@@ -1071,5 +1071,18 @@ m('load() import semantics')
 		A = B, false)
 )
 
+m('args() list')
+(
+	hasSuffix? := str.hasSuffix?
+
+	as := args()
+	t('args() returns a list'
+		type(as), 'composite')
+	t('first item in args() is the Ink executable'
+		hasSuffix?(as.0, 'ink'), true)
+	t('second item in args() is the test script'
+		hasSuffix?(as.1, 'test.ink'), true)
+)
+
 ` end test suite, print result `
 (s.end)()

utils/ink.vim

@@ -61,6 +61,7 @@ highlight link inkIdentifier Identifier
 syntax match builtinFunctionCall "\v[A-Za-z@!?][A-Za-z0-9@!?]*\(" contains=inkIdentifier,inkBuiltin,inkDelim
 syntax keyword inkBuiltin load contained
 
+syntax keyword inkBuiltin args contained
 syntax keyword inkBuiltin in contained
 syntax keyword inkBuiltin out contained
 syntax keyword inkBuiltin dir contained