lean4-htt/Lake/SearchPath.lean

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/-
Copyright (c) 2021 Mac Malone. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mac Malone
-/
import Lean.Util.Path
open System
namespace Lake
/--
Try to find the home of Lean by calling
`lean --print-prefix` and returning the path it prints.
-/
def getLeanHome? : IO (Option FilePath) := do
let out ← IO.Process.output {
cmd := "lean",
args := #["--print-prefix"]
}
if out.exitCode == 0 then
some <| FilePath.mk <| out.stdout.trim
else
none
/--
Try to get Lake's home by assuming
this executable is located at `<lake-home>/bin/lake`.
-/
def getLakeHome? : IO (Option FilePath) := do
(← IO.appPath).parent.bind FilePath.parent
/--
Check if Lake's executable is co-located with Lean, and, if so,
try to return their joint home by assuming they are located at `<app-home>/bin`.
-/
def getAppHome? : IO (Option FilePath) := do
let appPath ← IO.appPath
if let some appDir := appPath.parent then
let leanExe := appDir / "lean" |>.withExtension FilePath.exeExtension
if (← leanExe.pathExists) then
return appDir.parent
return none
/--
Initializes the search path the Lake executable
uses when interpreting package configuration files.
In order to use the Lean stdlib (e.g., `Init`),
the executable needs the search path to include the directory
with the stdlib's `.olean` files (e.g., from `<lean-home>/lib/lean`).
In order to use Lake's modules as well, the search path also
needs to include Lake's `.olean` files (e.g., from `build`).
While this can be done by having the user augment `LEAN_PATH` with
the necessary directories, Lake also intelligently derives an initial
search path from the location of the `lean` executable and itself.
If Lake is co-located with `lean` (i.e., there is `lean` executable
in the same directory as itself), it will assume it was installed with
Lean and that both Lean and Lake are located in `<lean-home>/bin` with
Lean's `.olean` files at `<lean-home/lib/lean` and Lake's at `.olean` files
at `<lean-home/lib/lake`.
Otherwise, it will run `lean --print-prefix` to find Lean's home and
assume that its `.olean` files are at `<lean-home>/lib/lean` and that `lake`
is at `<lake-home>/bin/lake` with its `.olean` files at `<lake-home>`.
If this is correct, the user will not need to augment `LEAN_PATH`.
-/
def setupLeanSearchPath : IO Unit := do
let mut sp : SearchPath := []
if let some appHome ← getAppHome? then
-- we are co-located with Lean
let libDir := appHome / "lib"
sp := libDir / "lean" :: libDir / "lake" :: sp
else
-- we are a custom installation
if let some lakeHome ← getLakeHome? then
sp := lakeHome :: sp
if let some leanHome ← getLeanHome? then
sp := leanHome / "lib" / "lean" :: sp
sp ← Lean.addSearchPathFromEnv sp
Lean.searchPathRef.set sp