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The Lean Language Reference
1.
Introduction
2.
Elaboration and Compilation
3.
The Lean Language
4.
Terms
5.
Monads and
do
-Notation
6.
IO
7.
Tactic Proofs
8.
The Simplifier
9.
Basic Types
10.
Standard Library
11.
Notations and Macros
12.
Output from Lean
13.
Elan
14.
Lake and Reservoir
Index
6.
IO
6.1.
Logical Model
6.2.
Control Structures
6.3.
Console Output
6.4.
Mutable References
6.5.
Files, File Handles, and Streams
6.6.
Environment Variables
6.7.
Timing
6.8.
Processes
6.9.
Random Numbers
6.10.
Tasks and Threads
6.6.
Environment Variables
Source Code
Report Issues
6.6. Environment Variables
🔗
IO.getEnv (var : String) :
BaseIO
(
Option
String
)