From fe8b60d2e800c5afbd68c4415de5aef74235fa02 Mon Sep 17 00:00:00 2001
From: John Jacobsen <eigenhombre@gmail.com>
Date: Thu, 22 Aug 2024 09:43:23 -0500
Subject: [PATCH] WIP adding argv. #96

---
 examples/galax.l1    |  5 +++--
 lisp/builtin.go      | 20 ++++++++++++++++++++
 lisp/builtin_test.go | 16 ++++++++++++++++
 lisp/examples.txt    |  1 +
 main.go              | 10 ++++------
 5 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/examples/galax.l1 b/examples/galax.l1
index 606516e..e5cb5e0 100644
--- a/examples/galax.l1
+++ b/examples/galax.l1
@@ -174,5 +174,6 @@
       darlena arlinda arlen junita margeret anette selina wilma reena
       tessa delma))
 
-(dotimes 10
-  (printl (itsalive (randchoice all-names))))
+(let ((n (number (or (caddr ARGV) 10))))
+  (dotimes n
+    (printl (itsalive (randchoice all-names)))))
diff --git a/lisp/builtin.go b/lisp/builtin.go
index 2fab1e3..ee9d296 100644
--- a/lisp/builtin.go
+++ b/lisp/builtin.go
@@ -31,6 +31,12 @@ func InitGlobals() Env {
 	globals.Set("BQUOTE", Atom{"`"})
 	globals.Set("DQUOTE", Atom{"\""})
 	globals.Set("UPLINE", Atom{"\033[F"})
+	// Form up ARGV:
+	var args []Sexpr
+	for _, arg := range os.Args {
+		args = append(args, Atom{arg})
+	}
+	globals.Set("ARGV", mkListAsConsWithCdr(args, Nil))
 	return globals
 }
 
@@ -882,6 +888,20 @@ func init() {
 				return Nil, nil
 			},
 		},
+		"number": {
+			Name:       "number",
+			Doc:        DOC("Cast an atom, probably from an external source, to a number. Mostly used for parsing ARGV."),
+			FixedArity: 1,
+			NAry:       false,
+			Args:       LC(A("x")),
+			Fn: func(args []Sexpr, _ *Env) (Sexpr, error) {
+				if len(args) != 1 {
+					return nil, baseError("number expects a single argument")
+				}
+				n := Num(args[0].String())
+				return n, nil
+			},
+		},
 		"print": {
 			Name:       "print",
 			Doc:        DOC("Print the arguments"),
diff --git a/lisp/builtin_test.go b/lisp/builtin_test.go
index 2b89ff9..466f8c0 100644
--- a/lisp/builtin_test.go
+++ b/lisp/builtin_test.go
@@ -68,3 +68,19 @@ func TestListFromSemver(t *testing.T) {
 		}
 	}
 }
+
+// Test that the number function returns the number it is given.
+// Primarily useful for handling argv values.
+func TestNumberTest(t *testing.T) {
+	// Emulate setting of an argv value:
+	env := mkEnv(nil)
+	env.Set("h", Atom{"100"})
+	// Check the function proper:
+	result, err := eval(Cons(Atom{"number"}, Cons(Atom{"h"}, Nil)), &env)
+	if err != nil {
+		t.Errorf("eval(num 100) = %q", err)
+	}
+	if !result.Equal(Num(100)) {
+		t.Errorf("eval(num 100) = %q", result)
+	}
+}
diff --git a/lisp/examples.txt b/lisp/examples.txt
index c2d8b22..ef68c43 100644
--- a/lisp/examples.txt
+++ b/lisp/examples.txt
@@ -103,6 +103,7 @@ l1 - a Lisp interpreter.
            not  N    1   Return t if the argument is nil, () otherwise
           not=  F    0+  Complement of = function
            nth  F    2   Find the nth value of a list, starting from zero
+        number  N    1   Cast an atom, probably from an external source, to a number. Mostly used for parsing ARGV.
        number?  N    1   Return true if the argument is a number, else ()
           odd?  F    1   Return true if the supplied integer argument is odd
             or  S    0+  Boolean or
diff --git a/main.go b/main.go
index 79c2fb3..e7462c7 100644
--- a/main.go
+++ b/main.go
@@ -104,12 +104,10 @@ func main() {
 
 	files := flag.Args()
 	if len(files) > 0 {
-		for _, file := range files {
-			err := lisp.LoadFile(&globals, file)
-			if err != nil {
-				fmt.Printf("ERROR:\n%v\n", err)
-				os.Exit(1)
-			}
+		err := lisp.LoadFile(&globals, files[0])
+		if err != nil {
+			fmt.Printf("ERROR:\n%v\n", err)
+			os.Exit(1)
 		}
 		return
 	}