fix #42 (hack? not sure)

src/core/editor/Ctx.re

@@ -167,6 +167,17 @@ let push_zigg = (~onto as d: Dir.t, zigg: Zigg.t, ~fill=Cell.empty, ctx: t) => {
   map_hd(Frame.Open.cat(rest), ctx);
 };
 
+let trim_space = (~side: Dir.t, ctx: t) =>
+  switch (pull(~from=side, ctx)) {
+  | (Node(tok), ctx) when Mtrl.is_space(tok.mtrl) =>
+    let tok =
+      Strings.chop_prefix(~prefix=" ", tok.text)
+      |> Option.map(text => {...tok, text})
+      |> Option.value(~default=tok);
+    Token.is_empty(tok) ? ctx : push(~onto=side, tok, ctx);
+  | _ => ctx
+  };
+
 let zip_toks = (~save_cursor=false, ctx: t): option((Meld.t, t)) => {
   let (hd, tl) = uncons(ctx);
   Frame.Open.zip_toks(~save_cursor, hd)

src/core/editor/Modify.re

@@ -295,6 +295,7 @@ let expand = (tok: Token.t) =>
 let try_expand = (s: string, z: Zipper.t): option(Zipper.t) => {
   open Options.Syntax;
   let* () = Options.of_bool(String.starts_with(~prefix=" ", s));
+  // todo: check if in middle of token
   let (face, rest) = Ctx.pull(~from=L, z.ctx);
   let* tok = Delim.is_tok(face);
   // if expandable, consider all expandable const labels
@@ -314,6 +315,7 @@ let try_expand = (s: string, z: Zipper.t): option(Zipper.t) => {
           )
     )
     |> Ctx.push(~onto=L, Token.space())
+    |> Ctx.trim_space(~side=R)
     |> finalize(~mode=Inserting(" "), ~fill=Cell.point(~dirty=true, Focus))
     |> return;
   };

src/stds/Strings.re

@@ -14,3 +14,5 @@ let count = c => Base.String.count(~f=(==)(c));
 let split = Base.String.split;
 
 let rev = Base.String.rev;
+
+let chop_prefix = Base.String.chop_prefix;