Documentation for the lambda calculus language

[denismerigoux]

Similar to the other .mld files in the folders of each intermediate representation, the lambda calculus should have its own .mld and appear in the general documentation diagram :

catala/src/catala/index.mld

Lines 13 to 47 in af8a7b1

	{v
	+---------------+
	| |
	| Surface AST |
	| |
	+---------------+
	|
	* Separate code from legislation |
	* Remove syntactic sugars |
	v
	+---------------+
	| |
	| Desugared AST |
	| |
	+---------------+
	|
	* Build rule trees for each definition |
	* Order variable computations inside scope |
	v
	+--------------------+
	| |
	| Scope language AST |
	| |
	+--------------------+
	|
	* Convert scopes into functions |
	* Thunking of subscope arguments |
	|
	v
	+----------------------+
	| |
	| Default calculus AST |
	| |
	+----------------------+ v}