Merge pull request #110 from morpho-org/fix/constants-1

refactor irm constants

src/libraries/adaptive-curve/ConstantsLib.sol

@@ -1,30 +1,31 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.0;
 
-import {WAD_INT} from "../MathLib.sol";
-
 /// @title ConstantsLib
 /// @author Morpho Labs
 /// @custom:contact security@morpho.org
 library ConstantsLib {
-    /// @notice 1 bps = 0.01% (scaled by WAD).
-    int256 public constant ONE_BPS = 0.0001 ether;
-
     /// @notice Curve steepness (scaled by WAD).
+    /// @dev Curve steepness = 4.
     int256 public constant CURVE_STEEPNESS = 4 ether;
 
     /// @notice Adjustment speed per second (scaled by WAD).
-    int256 public constant ADJUSTMENT_SPEED = int256(50 ether) / 365 days;
+    /// @dev Adjustment speed = 50/year.
+    int256 public constant ADJUSTMENT_SPEED = 50 ether / int256(365 days);
 
     /// @notice Target utilization (scaled by WAD).
+    /// @dev Target utilization = 90%.
     int256 public constant TARGET_UTILIZATION = 0.9 ether;
 
-    /// @notice Initial rate at target per second (scaled by WAD) (1% min APR / 16% max APR).
-    int256 public constant INITIAL_RATE_AT_TARGET = 4_00 * ONE_BPS / 365 days;
+    /// @notice Initial rate at target per second (scaled by WAD).
+    /// @dev Initial rate at target = 4% (rate between 1% and 16%).
+    int256 public constant INITIAL_RATE_AT_TARGET = 0.04 ether / int256(365 days);
 
-    /// @notice Minimum rate at target per second (scaled by WAD) (0.025% min APR).
-    int256 public constant MIN_RATE_AT_TARGET = 10 * ONE_BPS / 365 days;
+    /// @notice Minimum rate at target per second (scaled by WAD).
+    /// @dev Minimum rate at target = 0.1% (minimum rate = 0.025%).
+    int256 public constant MIN_RATE_AT_TARGET = 0.001 ether / int256(365 days);
 
-    /// @notice Maximum rate at target per second (scaled by WAD) (800% max APR).
-    int256 public constant MAX_RATE_AT_TARGET = 200_00 * ONE_BPS / 365 days;
+    /// @notice Maximum rate at target per second (scaled by WAD).
+    /// @dev Maximum rate at target = 200% (maximum rate = 800%).
+    int256 public constant MAX_RATE_AT_TARGET = 2.0 ether / int256(365 days);
 }