Documentation
¶
Overview ¶
Package closure provides closure transform for MIR representation.
Closure transform is a process to move all functions to toplevel of program. If a function does not contain any free variables, it can be moved to toplevel simply. But when containing any free variables, the function must take a closure struct as hidden parameter. And need to insert a code to make a closure at the definition point of the function.
In closure transform, it visits function's body assuming the function is a normal function. As the result of the visit, if some free variables found, it means that the function is actually not a normal function, but a closure. So restore the state and retry visiting its body after adding the function to closures list.
Note that applied normal functions are not free variables, but applied closures are free variables. Normal function is not a value but closure is a value. So, considering recursive functions, before visiting function's body, the function must be determined to normal function or closure. That's the reason to assume function is a normal function at first and then backtrack after if needed.
Example ¶
file := filepath.FromSlash("../testdata/from-mincaml/ack.ml")
src, err := locerr.NewSourceFromFile(file)
if err != nil {
// File not found
panic(err)
}
ast, err := syntax.Parse(src)
if err != nil {
// When parse failed
panic(err)
}
// Resolving symbols, type analysis and converting AST into MIR instruction block
env, block, err := sema.SemanticsCheck(ast)
if err != nil {
// Type error detected
panic(err)
}
// Closure transform.
// Move all nested function to toplevel with resolving closures and known
// function optimization.
// Returned value will represents converted whole program.
// It contains entry point of program, some toplevel functions and closure
// information.
program := Transform(block)
// For debug purpose, you can show MIR representation after conversion
program.Println(os.Stdout, env)
Output: ack$t1 = recfun x$t2,y$t3 ; type=int -> int -> int BEGIN: body (ack$t1) $k2 = int 0 ; type=int $k3 = binary <= x$t2 $k2 ; type=bool $k28 = if $k3 ; type=int BEGIN: then $k5 = int 1 ; type=int $k6 = binary + y$t3 $k5 ; type=int END: then BEGIN: else $k8 = int 0 ; type=int $k9 = binary <= y$t3 $k8 ; type=bool $k27 = if $k9 ; type=int BEGIN: then $k12 = int 1 ; type=int $k13 = binary - x$t2 $k12 ; type=int $k14 = int 1 ; type=int $k15 = app ack$t1 $k13,$k14 ; type=int END: then BEGIN: else $k18 = int 1 ; type=int $k19 = binary - x$t2 $k18 ; type=int $k23 = int 1 ; type=int $k24 = binary - y$t3 $k23 ; type=int $k25 = app ack$t1 x$t2,$k24 ; type=int $k26 = app ack$t1 $k19,$k25 ; type=int END: else END: else END: body (ack$t1) BEGIN: program $k31 = int 3 ; type=int $k32 = int 10 ; type=int $k33 = app ack$t1 $k31,$k32 ; type=int $k34 = appx print_int $k33 ; type=unit END: program
Index ¶
Examples ¶
Constants ¶
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Variables ¶
This section is empty.
Functions ¶
Types ¶
This section is empty.
Source Files