On 2016-05-31 09:56, Stephen J. Turnbull wrote: [snip]
It give me no clue what it's supposed to mean. In math the forward arrow is often used to name a function type (including the domain preceding the arrow and the codomain following it in the name), although what the parentheses and their contents mean, I don't know. The codomain type is the value of TypeVar()? What's that? In Pascal and R, the reverse arrow
T <- TypeVar()
is used to mean assignment (which you could read as "T receives TypeVar()", but the implicit argument on the RHS is a double-take for me in both syntaxes -- the argument to TypeVar is not optional!
FYI, in Pascal the assignment operator is ":=".
The assignment operator in APL is "←".