// Test equations can embed equation pieces built by functions
#let foo(v1, v2) = {
  // Return an equation piece that would've been rendered in
  // inline style if the piece is not embedded
  $v1 v2^2$
}
#let bar(v1, v2) = {
  // Return an equation piece that would've been rendered in
  // block style if the piece is not embedded
  $ v1 v2^2 $
}
#let baz(..sink) = {
  // Return an equation piece built by joining arrays
  sink.pos().map(x => $hat(#x)$).join(sym.and)
}

Inline $2 foo(alpha, (M+foo(a, b)))$.

Inline $2 bar(alpha, (M+foo(a, b)))$.

Inline $2 baz(x,y,baz(u, v))$.

$ 2 foo(alpha, (M+foo(a, b))) $
$ 2 bar(alpha, (M+foo(a, b))) $
$ 2 baz(x,y,baz(u, v)) $