[RFC] Relay IR Text Format

Keyword Proposal

The final keywords are:

• def for global function definitions
• fn for local function definitions/anonymous functions
• if and else for if-else expressions
• let for let bindings
• True and False for booleans
• data types are tvm-style. e.g. float32x4

Loose Ends

There are some elements of the text format that didn’t make it into this PR. See #1935 for details.

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Please comment on syntax design choices for #1781 here!

Notable Syntax Examples

Functions

Named, Typed

def @foo(%x: int64, %y: int64) -> int64 {
    %x + %y
}

Named, Inferred

def @foo(%x, %y) {
    %x + %y
}

Anonymous, Typed

fn (%x: int64, %y: int64) -> int64 {
    %x + %y
}

Anonymous, Inferred

fn (%x, %y) {
    %x + %y
}

Let Expressions and Mutation

Immutable

let %x = 2;
let %x = 3;
let %y = 4;
%x + %y

Side Effects Only

The following are equivalent

print("hello");
1

let %_ = print("hello");
1

Tuples

()
(0,)
(0, 1)

Types

Base Types

Designed to look like NumPy types.

int32
uint32
float32
bool
int32x4
...

Shape Types

unimplemented

s
(n + 1, 2 * n, 4)

Tensor Annotations

generics unimplemented

def @add(t1: Tensor[s, bt], t2: Tensor[s, bt]) -> Tensor[s,  bt] {
    ...
}

Function Types

fn (int32, int32) -> int32

[MarisaKirisame]

This idea just come out of my head: can we pin a version number to every relay source/serialized code? It help to switch from one version to another version.

[joshpoll]

I think using Python conventions for booleans and dtypes is probably the way to go.