First of all, don't panic! It is a long lesson that explains the basics of variables and storage manipulation. You are going to set up your spaceship storage and make yourself one step closer to your trip through magnificent TON Universe.

Ready? Here goes!

Types overview

FunC is static weakly typed language. TVM supports following types (don't care about it too much now):

• Integer - signed 257-bit integer (func: int).
• Cell - data piece of up to 1023 bits and up to 4 references to other cells; mostly used for persistent storage (func: cell).
• Tuple - an ordered collection of up to 255 components, having arbitrary value types(func: tuple).
• Null - a type with exactly one value, used for representing empty lists, empty branches of binary trees, absence of return value in some situations, and so on(not represented in func dirrectly).
• Slice - a contiguous “subcell” of an existing cell, containing some of its bits of data and some of its references. Essentially, a slice is a read-only view for a subcell of a cell(func: slice).
• Builder - an “incomplete” cell that supports fast operations of appending bitstrings and cell references at its end (func: builder).
• Continuation - an “execution token” for TVM, which may be invoked later (func: cont).

Declare variables

Variables are declared quite similar to other languages. Syntax is following:

type name = value;
type name = function_with_return_value();

Definition must to have right value. For example:

int number = 10;
cell dictionary = new_dict()

Parse slice

To read the data from slice the functions preload_TYPE and load_TYPE are provided. They are declared in stdlib.fc (note: don't care about it too much now).

(slice, int) ~load_int(slice s, int len) asm(s len -> 1 0) "LDIX";
(slice, int) ~load_uint(slice s, int len) asm( -> 1 0) "LDUX";
int preload_int(slice s, int len) asm "PLDIX";
int preload_uint(slice s, int len) asm "PLDUX";
(slice, (slice)) ~load_bits(slice s, int len) asm(s len -> 1 0) "LDSLICEX";
(slice, slice) load_bits(slice s, int len) asm(s len -> 1 0) "LDSLICEX";
slice preload_bits(slice s, int len) asm "PLDSLICEX";

To sum up: