The function type(expr, 'assignable') returns true if the expression expr can be assigned to; otherwise, it returns false.

If the parameter t is included, it checks that expr is also of that type.

An expression is assignable if one of the following is true:

- It is a symbol and it is not protected.

- It is of type indexed and its zeroth operand is either assignable or a table or an rtable.

- It is of type function and its zeroth operand is assignable.

$\mathrm{type}\left(x\left[0\right]\left(4\right)\,\mathrm{assignable}\right)$

$\mathrm{true}$

$x\left[0\right]\left(4\right)≔7$

$x_0\left(4\right)≔7$

$\mathrm{type}\left(x\left[0\right]\,\mathrm{assignable}\left(\mathrm{name}\right)\right)$

$\mathrm{true}$

$\mathrm{type}\left(f\left(x\right)\,\mathrm{assignable}\left(\mathrm{name}\right)\right)$

$\mathrm{false}$

$\mathrm{type}\left(\mathrm{true}\,\mathrm{assignable}\left(\mathrm{name}\right)\right)$

$\mathrm{false}$