Imports

Split programs across files with use:

ilo

use "math-lib.ilo"

All declarations from the imported file merge into a flat namespace - no modules, no qualification.

Full import

ilo

-- math-lib.ilo
dbl n:n>n;*n 2
half n:n>n;/n 2
sq n:n>n;*n n

ilo

-- main.ilo
use "math-lib.ilo"

round-trip n:n>n;h=half n;r=dbl h;+r 0
hyp-sq a:n b:n>n;sa=sq a;sb=sq b;+sa sb

Shell

ilo main.ilo round-trip 10
# -> 10

ilo main.ilo hyp-sq 3 4
# -> 25

Scoped imports

Import only specific functions with a bracketed list:

ilo

use "math-lib.ilo" [dbl sq]

Now only dbl and sq are available. half is not imported. Requesting a name that does not exist in the file is an error (ILO-P019).

Import rules

• Paths are relative to the importing file’s directory
• use must appear at the top of the file, before any function definitions
• Imports are transitive: if a.ilo uses b.ilo, then main.ilo using a.ilo gets b.ilo’s declarations too
• Circular imports are detected and reported as an error (ILO-P018)
• All imported functions are type-checked as part of the full program
• use in inline mode (no file context) is an error (ILO-P017)

Multi-file example

ilo

-- validators.ilo
positive n:n>b;>n 0
in-range n:n lo:n hi:n>b;a=>=n lo;b=<=n hi;?a{true:b;false:false}

ilo

-- app.ilo
use "validators.ilo" [positive in-range]

check-age age:n>t;?{positive age:?(in-range age 0 150){true:"valid";false:"out of range"};false:"negative"}