The implementation is based on the paper Algorithm W Step by Step, with the addition of n-tuples, custom operators and if expressions.
exp ::= x -- variable
| exp exp -- application
| exp `x` exp -- infix application
| exp op exp -- infix operation
| fun x0...xn -> exp -- anonymous function
| let x = exp in exp -- let binding
| if exp then exp else exp -- if expression
| exp, exp -- tuple
| i -- int literal
| b -- bool literal
| exp :: ty -- type annotation
ty ::= a0...an
| int
| bool
| unit
| ty -> ty
| ty * ty- Algorithm W Step by Step: Original paper
- Write you an inference in F#: Various type inference algorithm implemented in F#