From aa0485fe33204169724d020f9c5e3b91e558ab1e Mon Sep 17 00:00:00 2001
From: ubq323 <ubq323@ubq323.website>
Date: Tue, 23 Jul 2024 17:00:56 +0100
Subject: add pend builtin function

---
 doc.txt        |  4 ++++
 g.peg          |  6 +++---
 ideas          | 35 +++++++++++++++++++++++++++++++++++
 lib.c          | 17 ++++++++++++++++-
 tests/pend.bth | 25 +++++++++++++++++++++++++
 tests/pend.out | 19 +++++++++++++++++++
 6 files changed, 102 insertions(+), 4 deletions(-)
 create mode 100644 ideas
 create mode 100644 tests/pend.bth
 create mode 100644 tests/pend.out

diff --git a/doc.txt b/doc.txt
index fce7e9d..d65c981 100644
--- a/doc.txt
+++ b/doc.txt
@@ -43,6 +43,10 @@
 	(arr): create new empty array
 	(append a x): appends to array a, returns a
 	(len a): get length of array a
+	(, ...): pend. concatenates arrays, promotes non-arrays to arrays
+				(, [1 2 3] 4) -> [1 2 3 4]
+				(, [1 2 3] [4 5]) -> [1 2 3 4 5]
+				(, 10 20) -> [10 20]  etc
 
 # cmdline args
 	bth [-Dl] [-Dt] filenames...
diff --git a/g.peg b/g.peg
index 08ded48..84d907e 100644
--- a/g.peg
+++ b/g.peg
@@ -32,12 +32,12 @@ expr <-
 	/ a:array { $$ = a; }
 
 list <- { $$ = astnode_new_list(); }
-	'(' 
+	'(' _
 	( e:expr { astnode_append(&$$, e); }
 	 )*
 	')' _ 
 array <- { $$ = astnode_new_arr(); }
-	'['
+	'[' _
 	( e:expr { astnode_append(&$$, e); }
 	 )* 
 	 ']' _
@@ -46,7 +46,7 @@ number <- < [0-9]+ > (! ident_char) _  { $$ = astnode_new_num(atoi($1)); }
 ident <- < ident_char+ > _ { $$ = astnode_new_ident($1); }
 string <- '"' < [^"]* > '"' _ { $$ = astnode_new_string($1); }
 
-ident_char <- [-_a-zA-Z'+*/\\%=0-9<>!]
+ident_char <- [-_a-zA-Z'+*/\\%=0-9<>!,]
 _ <- [ \t\n]*
 
 
diff --git a/ideas b/ideas
new file mode 100644
index 0000000..9717cb6
--- /dev/null
+++ b/ideas
@@ -0,0 +1,35 @@
+(, a b)
+pend.
+concatenates arrays, but enlists anything that isnt already an array
+thus 
+	(, x xs) (, xs x) is like append or prepend
+	(, x y) is pair
+	(, x) is enlist
+	(, xs ys) is extend
+if you really want an array to be inside another array
+	you can do (, xs (, ys)) or equivalently (, xs [ys])
+	this is probably the rarer case so that's good
+this always returns (allocates) a new object. that's probably fine
+most of the time
+if you want it to modify inplace have a (,! ...) form
+but need to specify which one to modify ...
+	(,! x xs) (,! xs x) are unambiguous
+	but should (,! xs ys) copy ys to xs or vice versa?
+	maybe something like (,!< xs ys) (,!> xs ys) respectively
+	or maybe more generally (,! xs (! ys)) but that's uglier
+	(,! xs !ys) ???
+this also does string concatenation. 
+have a variant (,, ...) maybe that puts spaces in between
+have a variant that uniions hashes
+	does (, {'x 10} {'y 20}) do {'x 10 'y 20} or [{'x 10} {'y 20}] ?
+	probably see which is commoner
+
+
+
+separate strings from symbols
+symbols are atomic and interned
+strings are just arrays of characters (codepoints)
+
+
+
+
diff --git a/lib.c b/lib.c
index e070bc0..a1ca311 100644
--- a/lib.c
+++ b/lib.c
@@ -40,7 +40,21 @@ static Val fn_len(State *S, int nargs, Val *args) {
 	ObjArr *a = AS_ARR(args[0]);
 	return VAL_NUM(a->len);
 }
-
+static Val fn_pend(State *S, int nargs, Val *args) {
+	CHECK(nargs > 0, "need at least 1 arg to ,");
+	ObjArr *a = objarr_new(S);
+	for (int i = 0; i < nargs; i++) {
+		Val v = args[i];
+		if (!IS_ARR(v))
+			objarr_append(S, a, v);
+		else {
+			ObjArr *b = AS_ARR(v);
+			for (int j = 0; j < b->len; j++) 
+				objarr_append(S, a, b->d[j]);
+		}
+	}
+	return VAL_OBJ(a);
+}
 
 
 typedef struct {
@@ -55,6 +69,7 @@ static BuiltinFunc builtin_funcs[] = {
 	{ "arr", fn_arr },
 	{ "append", fn_append },
 	{ "len", fn_len },
+	{ ",", fn_pend },
 	{ 0 },
 };
 
diff --git a/tests/pend.bth b/tests/pend.bth
new file mode 100644
index 0000000..9a37f00
--- /dev/null
+++ b/tests/pend.bth
@@ -0,0 +1,25 @@
+(def xs [
+	(, 10)
+	(, [100 200])
+
+	(, 22 33)
+	(, 11 [111 222])
+	(, [333 444] 99)
+	(, [555 666] [777 888])
+
+	(, 10 11 12)
+	(, 10 11 [20 30])
+	(, 10 [222 333] 99)
+	(, 10 [22 33] [44 55])
+	(, [100 200] 33 44)
+	(, [100 200] 33 [444 555])
+	(, [100 200] [33 44] 55)
+	(, [100 200] [333 444] [555 666])
+
+	(, [])
+	(, [1])
+	(, 10 [])
+	(, [] 20)
+	(, [] [])	
+])
+(each (x xs) (say x))
diff --git a/tests/pend.out b/tests/pend.out
new file mode 100644
index 0000000..44239f7
--- /dev/null
+++ b/tests/pend.out
@@ -0,0 +1,19 @@
+[ 10 ]
+[ 100 200 ]
+[ 22 33 ]
+[ 11 111 222 ]
+[ 333 444 99 ]
+[ 555 666 777 888 ]
+[ 10 11 12 ]
+[ 10 11 20 30 ]
+[ 10 222 333 99 ]
+[ 10 22 33 44 55 ]
+[ 100 200 33 44 ]
+[ 100 200 33 444 555 ]
+[ 100 200 33 44 55 ]
+[ 100 200 333 444 555 666 ]
+[ ]
+[ 1 ]
+[ 10 ]
+[ 20 ]
+[ ]
-- 
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