>> about
imp is a mischievous implicit build system meant to be used in V scripts

>> features
- dependencies derived from what flows take and give
- skips unchanged flows, by mtime or content hash
- pre/post hooks
- script and flow flags
- generated clean and run flows
- checks for binaries, V modules and C libraries

>> install
v install https://git.vorelabs.dev/vorelabs/imp.git

>> usage
#!/usr/bin/env -S v run
import imp

const target = $if windows { 'hello.exe' } $else { 'hello' }

mut ctx := imp.new()
ctx.add_target(target)
ctx.add_flow(
	id:    'build'
	help:  'build the binary'
	takes: ['src']
	gives: [target]
	flags: [imp.Flag{id: 'prod', help: 'optimised build'}]
	flow:  fn (self imp.Flow) ! {
		mut args := ['v', '-o', target]
		if self.flag('prod') {
			args << '-prod'
		}
		args << 'src'
		imp.system_args(args)!
	}
)
ctx.add_auto_flow(.clean)
ctx.add_auto_flow(.run)
ctx.default(['build'])
ctx.flow()

>> flow fields
id     name to call it by
name   display name
help   help text
takes  input paths
gives  output paths
check  .mtime (default), .hash or .none
pre    []imp.FlowDep run before
post   []imp.FlowDep run after
flags  []imp.Flag read with self.flag
flow   fn (self imp.Flow) !

>> hooks
imp.FlowDep{id: 'clean'}                  skipped along with its flow
imp.FlowDep{id: 'clean', required: true}  always runs, pre before the skip check

>> flags
flags: [imp.Flag{id: 'prod'}]      self.flag('prod'), forces the flow to run
ctx.flag(id: 'android')            returns a bool, also readable with self.flag

>> checks
imp.check_binary(['tar'])
imp.check_v_modules(['ui2'])
imp.check_system_c_links(['mpv/client.h'], flags: ['-lmpv'])

all return a bool, panic: true ends the build instead

>> limits
- flags are boolean
- .mtime has whole seconds, ties rebuild, and forgets flags: clean after --prod
- .hash reads all inputs on every run, and keeps state in .imp, so gitignore it
- clean only knows the current targets
- check_system_c_links proves the flags work, not that they are complete

>> license
MIT